The Olympic Athletic Center of Athens Spiros Louis or OACA (OAKA)), is a sport facilities complex located at Marousi, in the north section of the city. The complex consists of five major venues as well as other supplementary sport facilities.

Marousi or Maroussi, also known as Amarousio (Αμαρούσιο), is a city and a suburb in the northeastern part of the Athens urban area, Greece. Marousi dates back to the era of the ancient Athenian Republic; its ancient name was Athmonon (Ἄθμονον) and it represented one of the 10 Athenian sub-cities. The area held a main ancient temple, where Amarysia Artemis, the goddess of hunting, was adored. Consequently the city's modern name derives from that of the goddess, Amarysia, which denotes the origin of the worship back in Amarynthos, Euboea. Its mayor is Theodoros Ampatzoglou, re-elected in 2023.