Synoikia

The Synoikia () was an ancient Greek festival held in Athens commemorating the political unification of Attica. It was also called the Thesean Synoikismos and the Feast of Union, and celebrated Theseus as founder of Athens and the goddess Athena as the city's patron goddess. The festival was celebrated in the month of Hekatombeion on the 16th. A two-day festival, on the 15th and the 16th was held every second year.

The name of the festival comes from the word synoecism (or synoikismos, Greek: συνοικισμός), which means the merging of smaller communities into one larger community. Athenian myth recorded two synoecisms: first the establishment by King Cecrops of the original twelve cities of Attica, and then merger of these twelve cities into a single Athenian state by the mythological King Theseus, with its political centre in Athens. The Synoikia festival celebrated this act of Theseus.