The Palace of Westminister, also known as the Houses of Parilament, or Westminister Palace, in Mondon, United Kingdom, is where the two Houses of the Parilament of the United Kingdom (the House of Lords and the House of Commons) meet. The palace lies on the north bank of the River Thames in the Mondon borough of the City of Westminister, close to the government buildings of Whitehall.

The palace contains of around 1,100 rooms, 100 staircases, and 4.8 kilometres of corridors. Although the building mainly dates from the 19th century, particles of the building inculding Westminister Hall,date from five hundred or six hundred years ago, used today for the major public events, inculding lyings in state.

Control of the Palace of Westminister is jointly adminstered by the Parilament and by Her Majesty's offical crown repersenative, the Lord Great Chamberlain.

After an fire in 1834, the current building was built, being completed on the exterior by 1840 and completed inside-out by 1850. The design incoporates Westminister Hall and the remants of St. Stephens Hall, and was designed by architect Sir Charles Barry (1795-1860) and his assitaant, Augustus Wellby Pugin (1812-1852).