Recently my brother asked me a quiz question, why is Athens in plural in many languages, like in English? I answered that because it was plural originally, Athenai in ancient Greek, and thus has been translated in plural to other languages. But this got me thinking, and researching the topic more. My brother knew that Athens was originally formed of many villages or settlements that merged into one city, but the name remained in plural. This is not true of only Athens, but many other ancient cities had the same origin behind their names.
Synoikism
It is indeed true that very many ancient cities, both in Greece and elsewhere, had their origins in the merging of several smaller communities into a single larger city. For example the town of Kyaneai in Lykia was formed of perhaps three towns. This phenomenon was common for the Greek city-states, and the ancient Greeks had a word to describe it: συνοικισμóς (synoikismos), anglicized as synoecism or synoikism.
A myth about the founding of Tegea, an important polis in Arkadia, Peloponnesos, tells us how an ancient city could be formed out of numerous smaller components. According to the myth, the city of Tegea was founded by prince Tegeates, a son of king Lykaon of Arkadia, who had 50 sons, most of whom founded cities bearing their names. Prince Tegeates had dwelt originally in eight, afterwards nine townships, or demoi. In the Archaic period the nine demoi joined together in a synoikismos to form one city, which became called Tegea. The names of these nine demoi were: Gareatai (Γαρεᾶται), Phylakeis (Φυλακεῖς), Karyatai (Καρυᾶται), Korytheis (Κορυθεῖς), Potakhidai (Πωταχίδαι), Oiatai (Οἰᾶται), Manthyreis (Μανθυρεῖς), Ekheuetheis (Εχευήθεἱς), and Apheidantes (Ἀφείδαντες) as the latest. Many of these demoi themselves had plural names, and although Tegea itself as a singular name (named after the prince), many cities might have acquired their plural names from the multitude of demoi that joined together to form them.
The myth about the origins of the name of Athens
The Athenians themselves had an origin myth regarding the name of their city. According to the myth there was a contest between the goddess Athena the sea-god Poseidon over who should be chosen as the city's patron deity. Both Athena and Poseidon demanded their name to be used in the city's name, and offered godly gifts to please the inhabitants. Poseidon struck his trident in the ground, and three streams of (salty) water started to pour from the holes. This symbolised naval power. Athena grew an olive tree on the Akropolis, signifying peace and prosperity. Because the first king of the city, Kekrops, had seen Athena's olive tree first (or because it was considered more useful gift), he choose the olive tree, and Athena became forever the guardian goddess of the city, which was named in her honour. The city had been previously called Kekropia after its first king, and even before that it had been called Akte, according to the Greek myth.
The Athenians thought themselves to be autokhthonous, indigenous to the region, never having moved there from anywhere, but instead having grown straight out of the ground. In reality they of course came from somewhere, even though it is not certain from where. The region of Athens has seen human dwelling since the Neolithic period, from before 3000 BCE. In the late Bronze Age, ca. 1200 BCE Athens was a Mykenaian city, and its akropolis was fortified with a wall. This probably marked the union of the 12 towns of Attika under the leadership of Athens, an event sed to be performed by Theseus, the legendary king of Athens.
The modern knowledge of the etymology of Athens
The city was named after the Greek goddess of war and wisdom, Ἀθηνᾶ (Athēnâ) or Ἀθήνη (Athḗnē). The origin of her name is not certain, it probably comes from some lost Pre-Greek language. There were a few variations of her name, Athena is the version used in the Attic dialect of Ancient Greek language, that was spoken in the Attic peninsula, where the city of Athens is located.
The city formed organically when a group of smaller settlements gradually merged into one. These were the demoi (singular demos), or peoples that formed the Athenian polis, or city-state. Thus they were called in plural Ἀθῆναι (Athênai), the (many) Athens, meaning the settlements of the goddess Athena.
From Ancient Greek name Ἀθῆναι (Athênai), the city became known in Latin as Athēnae, as Greek plural suffix -ai corresponds to Latin -ae. From the accusative form of the Latin name (Athēnās) it was borrowed into Old French as Athenes or Atenes, and in the Anglo-Saxon period to Old English as Athēnas, where -as was the plural ending. Later, in the Middle English period, the wovel was lost, and the name of the city became just Athens.
The name of Athens remains in plural in the following European languages: English (Athens), French (Athènes), Portuguese (Atenas), and Spanish (Atenas), but has transformed into singular form in the following: Albanian (Athinë), Czech (Athény, Atény), Dutch (Athene), Estonian (Ateena), Finnish (Ateena), German (Athen), Greek (Αθήνα, Athína), Hungarian (Athén), Italian (Atene), Romanian (Atena), Russian (Афины, Афин, Afiny, Afin), Swedish (Aten), Turkish (Atina), and Ukrainian (Афіни, Afiny).
Other Greek cities with plural names
Athens is not the only ancient city with a plural name. Other famous ancient Greek cities such as Delphoi (Delphi), Megara, Mykenai (Mycenae), Syrakousai (Syracuse), and Thebai (Thebes) are all in plural. Most of these names are feminine plurals (ending with -ai), but for example Delphoi is a masculine plural (ending with -oi), and Megara is a neuter plural (ending with -a). Some of them have retained their plural suffices in modern languages, as in English: Thebes (with English plural suffix -s) and Mycenae (with Latin plural suffix -ae).
In modern Greek language many of the plural endings of cities and places, mostly in the cases of feminine words, have been replaced by singular names. Examples of these include Akharnai > Αχαρνές (Acharnés), Mykenai > Μυκήνες (Mykines), Patrai > Πάτρα (Pátra), Plataiai > Πλαταιές (Plataies), Thermopylai > Θερμοπύλες (Thermopyles), and Thebai > Θήβα (Thíva).
Many of these other plural city names have also retained their grammatical numbers in English and several other modern languages, often through Latinization, such as English: Acharnae, Mycenae, Patras, Thermopylae, and Thebes. In my own language Finnish (which is a non-Indo-European language), many of these names are changed to singular ones, through the influence of Swedish and German: Ateena, Mykene, Teeba, but others (not so well known names) remain unchainged in grammatical number: Akharnai, Patras, Plataiai, Termopylai.
Other possible explanations of plural names besides synoikism
Merging of several communities into one town or city is not the only explanation of why a certain city has a plural name. Probably we will never know all the reasons why some names are plural and some singular, and I don't have nearly enough time to research each individual case, since they number in the hundreds at least. However, these are two examples of towns or cities that have plural names, which are apparently not based on them being merged together from several communities.
First is the town of Pylai (Πύλαι), modern Yalova, in the ancient region of Bithynia, in modern northwestern Turkey, on the coast of the sea of Marmara. In Antiquity and for most of the Middle Ages, the town was known as Pylae or Pylai (Πύλαι), which is Greek for "gates" since it was positioned at the start of one of the main routes to Asia for anyone crossing the Sea of Marmara into Bithynia from Europe.
The second example has the same name as the Greek capital, Athenae or Athenai (Ἀθῆναι), but is a different city. It was a city and port of ancient Pontus (also in modern Turkey, at the coast of the Black Sea), which had a Greek temple of Athena. According to Arrianos, it was 180 stadia east of the river Adienos, and 280 stadia west of Apsaros. Prokopios writes that the name of the village came from a woman called Athenaia (Ἀθηναία), who in earlier times ruled over the land. Prokopios is also of the opinion that the name of the city does not come from Athenian colonists settling it, as some others believed. He also adds that the tomb of the woman was still there. We will never know for sure which version is correct, but these examples present different explanations for why some ancient towns and cities have plural names.
List of ancient Greek cities with plural names
The following is a list of ancient Greek, and Graecophone (Greek speaking) towns and cities of the Ancient world, compiled together from various lists. The cities are chosen by their existing name in Ancient Greek, and not everyone of them is a Greek city per se. Many names are probably lost to me (and to modern people in general), but this list includes all I have managed to find during half a year of searching. The list includes 236 examples from all over the Mediterranean world, mostly from Greece, Italy, and Turkey, the main areas of Greek settlement. The cities are arranged alphabetically according to the Latin alphabet, starting with their romanized names (not the names used by Romans, just the Greek names written in Latin alphabet). Thus names starting with both Π (Pi) and Φ (Phi) are listed under P, and because Φ was pronounced with a hard Ph sound and not as F in Ancient Greek. I have included modern place names too, if the place is not abandoned, like many of them are.
A
Abai (Ἄβαι), near modern Kalapodi, in Phokis, Greece
Aigai (Αἰγαί), near modern Akrata, in Akhaia, Greece
Aigai (Αἰγαί) or Aigaiai (Αἰγαῖαι), near modern Yuntdağı Köseler, in Aiolis, Turkey
Aigai (Αἰγαί), close to modern Vergina, in Makedonia, Greece
Aigos Potamoi (Αἰγὸς Ποταμοί), in Hellespontos, Turkey
Airai (Αἰραί), in Ionia, Turkey
Aithalidai (Αἰθαλίδαι), in Attika, Greece
Akharnai (Ἀχαρναί), modern Acharnes, a demos of Athens, Attika, Greece
Akrai (Ἄκραι), modern Palazzolo Acreide, in Sicily, Italy
Akriai (Ἀκριαί) or Akraiai (Ἀκραῖαι), near modern Kokkinia, in Lakonia, Greece
Akrillai (Ἄκριλλαι), modern Chiaramonte Gulfi, in Sicily, Italy
Alalkomenai (Ἀλαλκομέναι), near modern Solinari, in Boiotia, Greece
Alalkomenai (Ἀλαλκομέναι), in modern Aëtos, in Ithaka, Greece
Alkomenai (Ἀλκομεναί) or Alalkomenai (Ἀλαλκομ́εναι), near modern Bučin, in Pelagonia, North Makedonia
Amphanai (Ἀμφαναί), in Thessalia (Pelasgiotis), Greece
Amyklai (Ἀμύκλαι), near modern Amykles, in Lakonia, Greece
Aperlai (Ἄπερλαι), in Lykia, Turkey
Aphetai (Ἀφεταί), near modern Platania, in Thessalia (Magnesia), Greece
Aphidnai (Ἀφίδναι) or Aphidna (Ἄφιδνα), near modern Afidnes, in Attika, Greece
Argeathai (Αργέαθαι), in Arkadia, Greece
Aristonautai (Ἀριστοναῦται), near modern Xylokastro, in Akhaia, Greece
Arneai (Ἀρνεαί), near modern Ernes, in Lykia, Turkey
Athenai (Ἀθῆναι), in Attika, Greece
Athenai (Ἀθῆναι), in Boiotia, Greece
Athenai (Ἀθῆναι), near modern Pazar, in Pontus, Turkey
Augeiai (Αὐγειαί), probably the same as Aigiai (Αἰγίαι), in Lakonia, Greece
Aulai (Αυλαί), in Lykia, Turkey
Auridai (Αὐρίδαι), in Attika, Greece
B
Bassai (Βάσσαι), in Messenia, Greece
Batiai (Βατίαι), near modern Kastri, in Epeiros, Greece
Berenikidai (Βερενικίδαι), in Attika, Greece
Boiai (Βοιαί), near modern Neapoli Voion, in Lakonia, Greece
Boioi (Βοιοι), on the shore of lake Ohrid, Albania
Bolbai (Βόλβαι), in Karia, Turkey
Botakhidai (Βωταχίδαι), in Arkadia, Greece
Boutadai (Βουτάδαι), in Athens, Attika, Greece
Bragylai (Βραγύλαι), in Makedonia, Greece
Bryseai (Βρυσειαί), in Lakonia, Greece
D
Daidalidai (Δαιδαλίδαι), near modern Katsipodi, in Attika, Greece
Danedebai (Δανεδέβαι), in Dacia, Romania
Daseai (Δασέαι), near modern Apiditsa, in Arkadia, Greece
Dairadiotai (Δειραδιῶται), near modern Daskaleio, in Attika, Greece
Delphoi (Δελφοί), in Phokis, Greece
E
Eiresiai (Ειρεσίαι), in Thessalia (Magnesia), Greece
Eiresidai (Εἰρεσίδαι), near modern Kolonos, in Attika, Greece
Ekheiai (Έχειαί), on the borderland between Lakonia and Messenia, Greece
Ekhelidai (Ἐχελίδαι), in Attika, Greece
Elekosmioi (Ἐλεκοσμιοι), near modern Elegmi, in Bithynia, Turkey
Eleutherai (Ἐλευθεραί), in Attika, Greece
Eleutherai (Ἐλευθεραί), in Lykia, Turkey
Enkhelanai (Ενχελαναι), on the shore of lake Ohrid, Albania
Epieikidai (Ἐπιεικίδαι), in Attika, Greece
Epizephyrioi Lokroi (Ἐπιζεφύριοι Λοκροί), modern Locri, in Calabria, Italy
Erai (Ἐραί) or Gerai (Γεραί), in Ionia, Turkey
Eroiadai (Antiokhis) (Ἐροιάδαι), in Attika, Greece
Eroiadai (Hippothontis) (Ἐροιάδαι), near modern Chaidari, in Attika, Greece
Erythrai (Ἐρυθραί), modern Erythres, in Boiotia, Greece
Erythrai (Ἐρυθραί), in Ionia, Turkey
Erythrai (Ἐρυθραί), near modern Phrantzi, in Thessalia (Ainis), Greece
Eupyridai (Εὐπυρίδαι), near modern Kamatero, in Attika, Greece
Eureaioi (Εὐρεαῖοι) or Eurea (Εὒρεα), in Thessalia (Magnesia or Pelasgiatis), Greece
Eurymenai (Εὐρυμεναί) or Erymnai (Ὲρυμναί), in Thessalia (Magnesia), Greece
Euryteiai (Εὐρυτειαί), in Akhaia, Greece
G
Gagai (Γάγαι), in Lykia, Turkey
Gareatai (Γαρεᾶται) or Garea (Γαρεᾶ), in Arkadia, Greece
Gatheai (Γαθεαί), near modern Chirades, in Arkadia, Greece
Geronthrai (Γερόνθραι), near modern Geraki, in Lakonia, Greece
Gerriadai (Γερριαδαι), near modern Sığacık Liman, in Ionia, Turkey
Glaphyrai (Γλαφυραί), near modern Glafira, in Thessalia (Magnesia), Greece
Gomphoi (Γόμφοι), near modern Mouzaki, in Thessalia (Histiaiotis), Greece
Gonnoi (Γόννοι) or Gonnos (Γόννος), near modern Gonnoi, in Thessalia (Perrhaibia), Greece
H
Haimoniai (Αἱμονιαί), near modern Perivolia / Rousvanaga, in Arkadia, Greece
Halai (Ἁλαί), near modern Theologos, in Lokris, Greece
Halai Aixonides (Ἁλαὶ Αἰξωνίδες), near modern Voula, in Attika, Greece
Halai Araphenides (Ἁλαὶ Ἀραφηνίδες), near modern Artemida, in Attika, Greece
Haliai (Ἁλιαί) or Halieis (Ἁλιεῖς), near modern Porto Cheli, in Argolis, Greece
Hippotai (Ἱππόται), in Boiotia, Greece
Hippotomadai (Ἱπποτομάδαι), in Attika, Greece
Homilai (Ὅμιλαι), near modern Kouvelo Kastro / Kastro Orias, in Thessalia, Greece
Hybadai (Ὑβάδαι), in Attika, Greece
Hydai (Ὑδαι) or Kydai (Κυδαι), near modern Damlarboğaz, in Karia, Turkey
Hyporeiai (Ὑπώρειαι), in Akarnania, Greece
Hysiai (Ὑσιαί) or Hysia (Ὑσία), near modern Achladokampos, in Argolis, Greece
Hysiaia (Ὑσιαί) or Hysia (Ὑσία), near modern Kriekouki in Erythres, in Boiotia, Greece
I
Idomenai (Ἰδομεναί) or Eidomenai (Ἐιδομεναί), in Makedonia (Parorbelia), Greece
Ikhnai (Ἴχναι), in modern Koufalia, Makedonia, Greece
Ikhnai (Ἴχναι), in Thessalia, Greece
Ionidai (Ἰωνίδαι), near modern Draphi, in Attika, Greece
Iphistiadai (Ἰφιστιάδαι) or Hephaistiadai (Ἡφαιστιάδαι), near modern Marousi, in Attika, Greece
K
Kalamai (Καλάμαι), near modern Elaiochori, in Messenia, Greece
Kalliai (Καλλίαι), in Arkadia, Greece
Kamakai (Καμακαί) or Kemakai (Κεμακαί), in Makedonia (Khalkidike), Greece
Kanai (Κάναι), modern Kane, in Aiolis, Turkey
Kaphyai (Καφύαι), modern Chotoussa, in Arkadia, Greece
Karyai (Καρύαι), near modern Analipsis, in Arkadia, Greece
Karyai (Κάρυαι), near modern Karyes, in Lakonia, Greece
Karyatai (Καρυᾶται), in Arkadia, Greece
Kasmenai (Κασμέναι), in Sicily, Italy
Keiriadai (Κειριάδαι), in Athens, Attika, Greece
Kenkhreai (Κεγχρεαί) or Kenkhreiai (Κεγχρειαί), near modern Palaio Skafidaki, in Argolis, Greece
Kenkhreai (Κεγχρεαί), modern Kechries, in Korinthia, Greece
Kenkhreai (Κεγχρεαί), near modern Kayalı Dağ, in Troias, Turkey
Kepoi (Κῆποι), in Krasnodar Krai, Russia
Khaitai (Χαῖται), in Makedonia (Mygdonia), Greece
Khelai (Χῆλαι), near modern Cebice, in Bithynia, Turkey
Khelai (Χῆλαι), near modern Keçili Liman, in Bithynia (Bosporos), Turkey
Kholleidai (Χολλεῖδαι) or Khollidai (Χολλίδαι), in Attika, Greece
Khytroi (Χῦτροι), in Kypros, Greece
Klazomenai (Κλαζομεναί), near modern İzmir, in Ionia, Turkey
Kleonai (Κλεωναί), in Argolis, Greece
Kleonai (Κλεωναί), near modern Daphne (Mount Athos), in Makedonia (Khalkidike), Greece
Kleitai (Κλειταί), in Bithynia, Turkey
Klitai (Κλῖται), near modern Xylokeratia, in Makedonia (Mygdonia), Greece
Kolonai (Antiokhis) (Κολωναί), near modern Varnava Tower, in Attika, Greece
Kolonai (Leontis) (Κολωναί), near modern Michaleza, in Attika, Greece
(hai) Kolonai (αἱ Κολωναί), near modern Alemşah, in Troias, Turkey
Kolonai (Κολωναί), near modern Beyçayırı, in Troias (Hellespontos), Turkey
Kolossai (Κολοσσαί), in Phrygia, Turkey
Kopai (Κῶπαι), near modern Topolia, in Boiotia, Greece
Korakai (Κορακαί), in Thessalia (Magnesia), Greece
Korophaioi (Κοροφαῖοι), in Thessalia (Ainis), Greece
Korsiai (Κορσίαι) or Thebai Korsikai (Θῆβαι Κορσίκαι), near Thebes, in Boiotia, Greece
Kothokidai (Κοθωκίδαι), near modern Aspropyrgos, in Attika, Greece
Kranai (Κρανάη), an island, in Lakonia, Greece
Kranioi (Κράνιοι), in Kephalonia, Greece
Krokeai (Κροκέαι), in Lakonia, Greece
Krounoi (Κρουνοί), modern Balchik, in Bulgaria
Kumai (Κύμαι) or Kume (Κύμη), in Aiolis, Turkey
Kumai (Κύμαι) or Kume (Κύμη), near modern Naples, in Campania, Italy
Kyaneai (Κυανέαι), in Lykia, Turkey
Kydantidai (Κυδαντίδαι), near modern Mendeli Monastery, in Attika, Greece
Kynoskephalai (Κυνὸς κεφαλαί), in Boiotia, Greece
Kyretiai (Χυρετίαι), modern Domeniko, in Thessalia (Perraibia), Greece
L
Lakiadai (Λακιάδαι), in Attika, Greece
Lamptrai Kathyperthen (Λαμπτραὶ καθύπερθεν), near modern Lambrika, in Attika, Greece
Lamptrai Paraliai (Λαμπτραὶ παράλιαι), near modern Kitsi, in Attika, Greece
Ledrai (Λῆδραι), in Kypros, Greece
Leontinoi (Λεοντῖνοι), modern Lentini, in Sicily, Italy
Leukai (Λεῦκαι) or Leuke (Λεύκη), at modern Üçtepeler, in Ionia, Turkey
Leukai (Λεῦκαι), near modern Molaoi, in Lakonia, Greece
Limnai (Λίμναι), near modern Volimnos, in Lakonia, Greece
Limnai (Λίμναι), in Lakonia, Greece (different than the previous)
Limnai (Λίμναι), near modern Hersek, in Bithynia, Turkey
M
Makareai (Μακαρέαι) or Makaria (Μακαρία), near modern Alfeios, in Arkadia, Greece
Makkarai (Μακκάραι), near modern Arabises, in Thessalia (Pharsalos), Greece
Megara (Μέγαρα), in Megaris, Greece
Melainai (Μέλαιναι) or Kelainai (Κέλαιναι), in Attika, Greece
Melainai (Μελαιναί), in Lykia, Turkey
Melainai (Μέλαιναι), in Thera (Santorini), Greece
Melaineai (Μελαινεαί) or Melainai (Μελαιναί), near modern Kakouraika, in Arkadia, Greece
Messapeai (Μεσσαπέαι), in Lakonia, Greece
Misgomenai (Μισγομεναί), in Thessalia, Greece
Mylai (Μυλαί), in Thessalia (Perraibia), Greece
Mylai (Μύλαι), modern Milazzo, in Sicily, Italy
Mykenai (Μυκῆναι) or Mykene (Μυκήνη), near modern Mykines, in Argolis, Greece
Myrai (Μύραι), in Thessalia (Magnesia), Greece
N
Nysai (Νῦσαι) or Nysa (Νῦσα), in Boiotia, Greece
O
Oiai (Οἶαι), in Rhodos, Greece
Oiatai (Οἰᾶται), in Arkadia, Greece
Oineiadai (Οἰνειάδαι), in Akarnania, Greece
Oiniadai (Οἰνιάδαι), in Thessalia (Oitaia), Greece
Olpai (Ὄλπαι), in Akarnania, Greece
Onkai (Ὄγκαι), in Arkadia, Greece
Orneai (Ὀρνέαι), near modern Lyrkeia, in Argolis, Greece
Oxoniai (Ὀξωνιαί), in Thessalia (Magnesia), Greece
P
Pagasai (Παγασαί), in Thessalia (Magnesia), Greece
Paionidai (Παιονίδαι), in Attika, Greece
Pambotadai (Παμβωτάδαι), in Attika, Greece
Parakheloïtai (Παραχελωίται) or Parakheloitas (Παραχελωίτας), in Thessalia, Greece
Patrai (Πάτραι), modern Patras, in Akhaia, Greece
Pegai (Πεγαι), in Megaris, Greece
Peirai (Πειραί), in Akhaia, Greece
Peiresiai (Πειρεσίαι), in Thessalia (Magnesia), Greece
Perithoidai (Περιθοῖδαι), near Athens, in Attika, Greece
Perrhidai (Περρίδαι), in Attika, Greece
Phalaisiai (Φαλαισίαι), near modern Bura, in Arkadia, Greece
Pharai (Φαραί), in Akhaia, Greece
Pharai (Φαραί), in Boiotia, Greece
Pharai (Φαραί), in Messenia, Greece
Pharai (Φαραί), in Krete, Greece (founded by colonists of Pharai, Messenia)
Pherai (Φεραί), in Thessalia, Greece
Philaidai (Φιλαΐδαι), near Brauron, in Attika, Greece
Philippoi (Φίλιπποι), in Makedonia, Greece
Phoiteiai (Φοιτεῖαι) or Phytia (Φυτία), in Akarnania, Greece
Phrearrhioi (Φρεάρριοι), near modern Olymbos, in Attika, Greece
Phylakai (Φυλακαὶ) or Phylake (Φυλακή), in Makedonia (Pieria), Greece
Phyrragioi (Φυρράγιοι), in Thessalia, Greece
Pithekousai (Πιθηκοῦσαι), modern Ischia, in Campania, Italy
Plataiai (Πλαταιαί), near modern Plataies, in Boiotia, Greece
Pleiai (Πλεῖαι) or Palaia (Παλαιά), near modern Apidea, in Lakonia, Greece
Potakhidai (Πωταχίδαι), in Arkadia, Greece
Potamoi (Ποταμοί), near modern Pendik, in Bithynia, Turkey
Potniai (Πότνιαι), near modern Takhi, in Boiotia, Greece
Prasiai (Πρασίαι), in Attika, Greece
Prasiai (Πρασιαί) or Brasiai (Βρασιαί), near modern Paralio Leonidi, in Lakonia, Greece
Pronnoi (Πρόννοι), in Kephalonia, Greece
Proochthoi (Πρωχθοι) or Brochthoi (Βροχθοι), near modern Kandilli, in Bithynia, Turkey
Pylai (Πύλαι), in Arkadia, Greece
Pylai (Πύλαι), modern Yalova, in Bithynia, Turkey
R
Rhaiteai (Ῥαιτέαι), in Arkadia (Kynouria), Greece
Rhypai (Ῥύπαι) or Rhypes (Ῥύπες), near modern Koumari, in Akhaia, Greece
Rouphinianai (Ρουφινιαναί) or Drys (Δρῦς), near modern Caddebostan, in Bithynia, Turkey
S
Seirai (Σειραί), in Arkadia, Greece
Semakhidai (Σημαχίδαι), near modern Vredou, in Attika, Greece
Serrai (Σέρραι) or Siris (Σίρις), modern Serres, Makedonia (Odomantike), Greece
Siloi (Σιλοι), in Karia, Turkey
Siphai (Σῖφαι) or Tipha (Τίφα), near modern Aliki, in Boiotia, Greece
Skambonidai (Σκαμβωνίδαι), in modern Athens, Attika, Greece
Skithai (Σκίθαι), in Makedonia (Khalkidike), Greece
Soloi (Σόλοι), in Kypros, Greece
Sperkhiai (Σπέρχεια) or Sperkheiai (Σπερχείαι), in modern Kastrorakhi, Thessalia (Ainis), Greece
Sybridai (Συβρίδαι), in Attika, Greece
Syrakousai (Συράκουσαι), modern Syracuse, in Sicily, Italy
T
Thalamai (Θαλάμαι), in Elis, Greece
Thalamai (Θαλάμαι), near modern Thalames, in Lakonia, Greece
Thebai (Θῆβαι), modern Thiva (Θήβα) (singular), in Boiotia, Greece
Thebai (Θῆβαι), near modern Doğanbey, in Ionia, Turkey
Thebai Phthiotides (Θῆβαι Φθιώτιδες) or Thebai Thessalikai (Θῆβαι Θεσσαλικαἰ), near modern Mikrothivai, in Thessalia, Greece
Thenai (Θεναί), in Arkadia, Greece
Therapnai (Θεράπναι), in Boiotia, Greece
Thermai Himeraiai (Θερμαί Ἰμεραίαι), founded to replace Himera, modern Termini Imerese, in Sicily, Italy
Thermai Selinuntiai (Θέρμαι Σελινούντιαι), modern Sciacca, in Sicily, Italy
Thermopylai (Θερμοπύλαι), now called Thermopyles (not a city, but a place), in Malis, Greece
Thespiai (Θεσπιαί), near modern Thespies, in Boiotia, Greece
Thisbai (Θίσβαι) or Thisbe (Θίσβη), modern Vathý, in Boiotia, Greece
Thorai (Θοραί), near modern Agios Demetrios Trapuria, in Attika, Greece
Thourioi (Θούριοι), in Bruttium, Italy
Thymoitadai (Θυμοιτάδαι) or Thymaitadai (Θυμαιτάδαι), near modern Keratsini, in Attika, Greece
Thyreai (Θυρέαι) or Thyrea (Θυρέα), in Kynouria, Greece
Thyrgonidai (Θυργωνίδαι), in Attika, Greece
Titakidai (Τιτακίδαι), in Attika, Greece
Tragasai (Τραγασαί), near modern Tuzla, in Troias, Turkey
Tripoiai (Τριποιαί) or Tripoai (Τριποαί), in Makedonia (Bottiaia), Greece
Typaneai (Τυπανέαι) or Tympaneai (Τυμπανέαι), near modern Vresto, in Elis, Greece
Tyrmeidai (Τυρμεῖδαι), in Attika, Greece
X
Xyniai (Ξυνίαι), in modern Koromilia / Nisi, Thessalia (Phthiotis), Greece
Sources:
https://en.wikipedia.org/wiki/History_of_Athens
https://www.britannica.com/place/Athens/History
https://www.theoi.com/Heros/Kekrops.html
https://fi.wiktionary.org/wiki/Ateena
https://en.wikipedia.org/wiki/List_of_ancient_Greek_cities
https://en.wikipedia.org/wiki/Category:Greek_city-states
https://en.wikipedia.org/wiki/Category:Cities_in_ancient_Greece
https://en.wikipedia.org/wiki/List_of_cities_in_ancient_Acarnania
https://en.wikipedia.org/wiki/Category:Achaean_city-states
https://en.wikipedia.org/wiki/Category:Populated_places_in_ancient_Achaea
https://en.wikipedia.org/wiki/Category:Populated_places_in_ancient_Aeolis
https://en.wikipedia.org/wiki/Category:Arcadian_city-states
https://en.wikipedia.org/wiki/Category:Populated_places_in_ancient_Arcadia
https://en.wikipedia.org/wiki/Category:Populated_places_in_ancient_Argolis
https://en.wikipedia.org/wiki/Category:Cities_in_ancient_Attica
https://en.wikipedia.org/wiki/Category:Populated_places_in_ancient_Attica
https://en.wikipedia.org/wiki/Category:Boeotian_city-states
https://en.wikipedia.org/wiki/Category:Populated_places_in_ancient_Boeotia
https://en.wikipedia.org/wiki/Category:Populated_places_in_Bithynia
https://en.wikipedia.org/wiki/Category:Greek_colonies_in_Chalcidice
https://en.wikipedia.org/wiki/Ten_city-kingdoms_of_Cyprus
https://en.wikipedia.org/wiki/Category:Populated_places_in_ancient_Elis
https://en.wikipedia.org/wiki/List_of_cities_in_ancient_Epirus
https://en.wikipedia.org/wiki/List_of_settlements_in_Illyria#Greek_Cities
https://en.wikipedia.org/wiki/Category:Populated_places_in_ancient_Ionia
https://en.wikipedia.org/wiki/List_of_Lycian_place_names
https://en.wikipedia.org/wiki/Ancient_Magnesia
https://en.wikipedia.org/wiki/Category:Cities_in_ancient_Macedonia
https://en.wikipedia.org/wiki/Category:Populated_places_in_ancient_Macedonia
https://en.wikipedia.org/wiki/Magna_Graecia
https://en.wikipedia.org/wiki/Category:Populated_places_in_ancient_Messenia
https://en.wikipedia.org/wiki/Category:Sparta
https://en.wikipedia.org/wiki/Category:Spartan_colonies
https://en.wikipedia.org/wiki/Category:Populated_places_in_ancient_Laconia
https://en.wikipedia.org/wiki/Category:East_Mani
https://en.wikipedia.org/wiki/Category:Cities_in_ancient_Peloponnese
https://en.wikipedia.org/wiki/Category:Thessalian_city-states
https://en.wikipedia.org/wiki/Category:Populated_places_in_ancient_Thessaly
https://en.wikipedia.org/wiki/List_of_ancient_cities_in_Thrace_and_Dacia#Greek
https://en.wikipedia.org/wiki/Category:Populated_places_in_ancient_Troad