Alfréd Hajós National Swimming Stadium, Swimming stadium on Margaret Island, Hungary

The Alfréd Hajós National Swimming Stadium is an aquatics complex on Margaret Island in Budapest, covering about 80,000 square metres over four floors, with eight indoor and outdoor pools. The indoor hall of 1930 holds a 33-metre pool, widened in 1983 by a retractable partition for 25-metre races. The outdoor pool and diving facility of 1937 were joined in 2006 by the Széchy Tamás pool, a 50-metre outdoor basin with a diving tower.

The facility opened in 1930 based on designs by Olympic gold medalist swimmer Alfréd Hajós, from whom it takes its name. Its opening marked the beginning of a new era for organized competitive swimming in Hungary.

The pools carry the name of Alfréd Hajós, who won two gold medals in swimming at the 1896 Athens Olympics and later designed the indoor hall himself. The complex has hosted the European Aquatics Championships in 1958, 2006 and 2010, and the 2017 World Aquatics Championships water polo and swimming events. The 1937 Horthy Cup water polo match against Germany, won 3:1 by Hungary, was played here.

The complex sits on Margaret Island, reachable on foot from the Árpád Bridge or by the island's bus line. The 1930 indoor hall and the outdoor pools are separate areas, so check which section is open before setting out. The 2006 Széchy Tamás section added the 50-metre outdoor pool and a diving pool behind the original building.

Alfréd Hajós won Hungary's first Olympic swimming gold medals in 1896, then designed this stadium himself in 1930. Its reinforced concrete arches were engineered by Eszter Pécsi, Hungary's first female architect and structural engineer. The indoor hall, 33 m by 18 m, was Europe's largest when it opened on 7 December 1930.