Athens Olympic Sports Complex

The Olympic Athletic Center of Athens Spiros Louis (Greek: Ολυμπιακό Αθλητικό Κέντρο Αθηνών "Σπύρος Λούης", Olympiakó Athlitikó Kéntro Athinón "Spýros Loúis") or OACA (OAKA)), is a sports complex located in Marousi, Athens. The complex consists of five major venues as well as other supplementary sport facilities.

The complex has hosted the , the World Championship in Athletics in 1997 as well as other important athletic and cultural events. Most notably, the complex was the main venue for the 2004 Summer Olympics. The complex was revamped for the games under a design produced by the Spanish architect Santiago Calatrava.