The Royal Castle in Warsaw (Polish: Zamek Królewski w Warszawie) is a castle residency that formerly served throughout the centuries as the official residence of the Polish monarchs. It is located in the Castle Square, at the entrance to the Warsaw Old Town. The personal offices of the king and the administrative offices of the Royal Court of Poland were located there from the sixteenth century until the Partitions of Poland.

Initially the complex served as the residence of the Dukes of Masovia, and since the sixteenth century, the seat of the Polish-Lithuanian Commonwealth: the King and Parliament (Chamber of Deputies and Senate). In its long history the Royal Castle was repeatedly plundered and devastated by the invading Swedish, Brandenburgian, Prussian and Tsarist armies. The Constitution of 3 May 1791, the first of its type in Europe and the world's second-oldest codified national constitution after the 1789 U.S. Constitution, was drafted here by the Four-Year Sejm.[2] In the 19th century, after the collapse of the November Uprising, it was used as an administrative centre by the Tsar and was re-designed for the needs of the Imperial Russian administration. During the course of World War I it was the residence of the German Governor-General. In 1920-1922 the Royal Castle was the seat of the Polish Head of State and between 1926 and World War II the building was the residence of the Polish president, Ignacy Mościcki.

Burned and looted by the Nazi Germans following the Invasion of Poland in 1939 and almost completely destroyed in 1944 after the failed Warsaw Uprising, the Castle was completely rebuilt and reconstructed; in 1965 the surviving fragments of the castle and the Royal Library, the adjacent Copper-Roof Palace and the Kubicki Arcades were registered as historical monuments by the government. Reconstruction of the castle carried out in 1971-1984 was led by the Civic Committee, responsible for the reconstruction of Warsaw. It was afforded by mainly US donations. In 1980, the Royal Castle, together with the Old Town was registered as a protected UNESCO World Heritage Site. Today it is a historical and national monument, and is listed as a national museum visited by over 500,000 people every year.[3]

The Royal Castle, due to its iconic appearance and its long history, is one of Warsaw's most recognizable landmarks.