The Belvedere first underwent major reconstruction in 1819–1822 when Grand Duke Constantine, the tsarist viceroy in Russian-occupied Poland, decided to make it his residence. The baroque structure was remodelled in the classicist style. To the building's main hull two one-floor perpendicular wings were added. The façade and garden wall were enhanced with monumental columned porticoes. Elements of the original décor have survived to this day in the palace's interior, particularly in the Blue Room, known as the Pompeii Room, and the Drawing-Room. Many pieces of furniture and other smaller historic items have also survived. Until recently, the Belvedere was the seat of the President of Poland.