The Royal Castle on Castle Square was the official residence of the Polish monarchs and seat of the Polish parliament for centuries. Completely destroyed by the Nazis after the 1944 Uprising, it was rebuilt between 1971 and 1984 using private donations from Polish citizens. The reconstruction is a remarkable achievement: the interior contains original furnishings, paintings, and decorative elements that were saved and hidden before the Germans demolished the building.
The castle's collection includes the Canaletto Room, hung with 23 paintings of 18th-century Warsaw by Bernardo Bellotto (nephew of the famous Canaletto). These views were used directly as architectural blueprints when the Old Town was reconstructed after the war — without them, the reconstruction would have been impossible. The Lanckoroński collection of two Rembrandt portraits is also housed here.