The Citadel is an impressive 19th century fortress, and one of the best-preserved buildings of defensive architecture in Poland.

The fortress survived the war and in 1945 became again Polish Army property.

The permanent collections include: Prisioner of X Pavilion of the Warsaw Citadel, Jozef Pilsudski in the X Pavilion and Siberians 1940-1956.

In the Museum of X Pavilion in the Warsaw Citadel there is a collection of paintings by Aleksander Sochaczewski (Lejb Sonder). These include: "Leaving Europe", "Runaway", "In the snow desert", "Road to slavery", "A scene of an exile's life", "On a level", "Old man sitting on a wheelbarrow". Regular exhibition includes information about Jewish prisoners of the Citadel: Isaack Kramsztyk, Beer Meisels, Marcus Jastrow.