Rotunda Zamość, Museum of martyrdom in a 19th-century fortress rotunda in Zamość, Poland

Rotunda Zamość is a ring-shaped brick-and-stone fortification with walls about 9.5 m high and 7 m thick, built on a 54 m diameter circle. Its inner courtyard, 38.5 m across, is surrounded by 19 connected cells; a twentieth was destroyed by bombing in September 1939. The structure is open toward the Old Town, and a moat still runs along its west, south and east sides.

French General Jean-Baptiste Mallet de Grandville designed this fortification between 1825 and 1831 as part of the Zamość Fortress complex. During World War II, the German occupiers converted it into a prison facility.

The museum, founded in 1947 as the Museum of Martyrdom of the Zamość Region, occupies the 19 cells of the ring. Each cell is dedicated to a different group of victims, among them the Wołyń deportees, lawyers and judges, scouts, teachers, postal workers and the prisoners of Majdanek and Auschwitz-Birkenau. Anniversary ceremonies tied to state and church holidays are held at the Rotunda.

The Rotunda stands about 500 m south of the Old Town, reached by a road running south from the former Bastion II; a moat still surrounds it on the west, south and east. The gate into the courtyard keeps its original German inscription, and the ruined cell destroyed in the September 1939 bombing lies to the left of the entrance. The war cemetery, with quarters for Polish Army, Home Army, Red Army, Jewish and Stalinist-era victims, lies outside the walls and along the road to the courtyard.

The gate at the courtyard entrance keeps its original German inscription: "Gefangenen Durchgangslager Sicherheitspol", with a smaller line noting the site was seized in agreement with the Zamość commandant's office. In the place of one cell destroyed by German bombing in September 1939, a plaque commemorates the shootings of prisoners.