O.A.C.A. Olympic Indoor Hall, Arena in Marousi, Athens, Greece

The O.A.C.A. Olympic Indoor Hall is a 19,000-capacity indoor arena in Marousi, northern Athens, completed in 1994 and renovated for the 2004 Summer Olympics. Its A-frame roof rests on four pillars 35 metres tall set 108 metres apart, and the building is designed to admit abundant natural light. Inside, steep banks of green seats rise on all sides above the white playing floor, with a video cube and banners overhead.

Completed in 1994, the hall was renovated on a large scale for the 2004 Summer Olympics, work finished on 30 June 2004 and the venue reopened on 10 August 2004, hosting artistic gymnastics, trampolining and the basketball finals. In 2023 Panathinaikos B.C. took a 49-year concession, and in August 2025 a five-year deal with Telekom Greece rebranded it Telekom Center Athens.

The arena is the home court of Panathinaikos and of the senior Greek national basketball team. Its name recalls the 1994 completion of the building, and the upper stand carries a banner reading "GATE 13 1966". On 18 and 20 May 2006 it hosted the 51st Eurovision Song Contest, with 15,000 seats available for the semifinal and the final.

The hall is easy to reach by public transport, and parking is available nearby for those arriving by car. Wide corridors and elevators inside make it straightforward to get around, including for visitors with mobility needs.

The arena's A-frame roof rests on four pillars 35 metres tall, set 108 metres apart, and its design lets daylight into the hall. The Greek Ministry of Sports calls it the largest indoor arena of its kind in the world. Look for the "GATE 13 1966" banner above the stands.