Sellasia is located at the foothills of Parnonas, 14.5 km north of Sparta. The village owes its name to the homonymous ancient settlement on the Paleogoulas hill. Traces of a fortress from the Hellenistic period have been found on the neighbouring hill of Agios Konstantinos.
In ancient times, there was a Spartan outpost in the area to control the passage to Laconia. In the adjacent plain, which is watered by Oinos, in 222 BC, a battle took place which closed the city-state chapter of Greek History. Antigonus III Dosson (Regent of Macedonia) and the Achaean Confederation fought with the Spartans under the rule of reformist King Cleomenes III. Sparta was the last city-state to continue to resist, both in the power of the Macedonians and in the Achaean Confederation. Spartans were defeated, and the allied forces included the conquered city in the Achaean Confederation.
Every year at the beginning of August, and for three days, the "Olive and Oil Festival" takes place in the village with exhibitions, discussions, artistic and musical events. Among the exhibits are artistic creations from wood and olive leaves. The celebration also has an educational character because the history of the olive tree and its products is promoted.
In June, on the celebration of the Holy Spirit, a festival is held in the central square of the village during which there is lots of live entertainment with music and dances until the morning hours.
Finally, Sellasia is the place of origin of the Giannakopoulos business family.
