The Rotunda is the place where during the Second World War the Gestapo investigation prison was housed.
The canon place was built between 1825-1831 as a defensive stance forwarded 500 m south of the city walls. The mighty walls in the shape of a ring with a diameter of 54 m with an inner courtyard are high at 9.5 m was provided with a shooting windows. The canon place was connected with the city by the path enclosed with ramparts, along with the moat of approximately 6 m width.
Up to the year 1939 the building served as a gunpowder magazine. In 1940 it served as a Gestapo investigation prison for the upper class of Zamosc. According to the estimates, about 8 thousand prisoners were shot and their bodies were burned here. On the cemetery around the Rotunda there are ashes of more than 45 thousand people. In April 1947 the Zamojszczyna Martyrs Mausoleum - Rotunda Museum was opened here.