The Old Synagogue is an Orthodox temple in the Kazimierz district and a valuable landmark of Jewish architecture in Europe. Until the Nazi invasion of Poland in 1939, it was the main religious, social, and organizational centre of the local Jewish community. Today it serves as a branch of the Historical Museum of Kraków, showcasing Jewish heritage.
The synagogue was built in 1407 or 1492; the date varies with several sources. In 1794 General Tadeusz Kościuszko spoke from the synagogue to gain the Jewish support in the struggle for Polish independence. The temple was ransacked by the Nazis during World War II and used as a magazine. In 1943, 30 Polish hostages were executed at its wall.
The original, largely Gothic synagogue underwent major refurbishment in 1570, conducted under the guidance of Italian architect Mateo Gucci. His design featured several fortifications, which today make the Old Synagogue a rare, surviving example of a Polish Fortress synagogue.
The rebuilding of 1570 included the attic wall with loopholes, windows placed far above ground level, and thick, masonry walls with heavy buttressing to withstand siege, all features borrowed from military architecture.