The Houses of Parliament, also known as the Palace of Westminster or Westminster Palace, is where the Parliament of the United Kingdom meet.

Buildings have occupied the site of the Houses of Parliament since at least Saxon times, though the oldest building still in existence date from about 1097. Edward the Confessor established the origins of the present buildings by building a royal place on the site from 1050, and Westminster was the main London residence of successive monarchs until the royal residence was moved to Whitehall Palace in 1547. In 1834 a fire broke out which destroyed much of the old palace, and all that remained was the chapel crypt, The Jewel Tower and Westminster Hall. After the fire in 1834, the present Houses of Parliament was built over the next 30 years.

The present Palace contains around 1,100 rooms, 100 staircases and 4.8 kilometers (3 mi) of corridors. The Palace of Westminster includes several towers. The tallest is the 98.5 meter (323 ft) Victoria Tower, a square tower at the south-western end of the Palace. Over the middle of the Palace, immediately above the Central Lobby, stands the octagonal Central Tower. It is 91.4 meters (300 ft) tall. At the north-eastern end of the Palace is the most famous of the towers, the Clock Tower, commonly known as Big Ben after its main bell. The Clock Tower is 96.3 meters (316 ft) tall. The tower houses five bells, which strike the Westminster Chimes every quarter hour. The largest and most famous of the bells is Big Ben, which strikes the hour.

Westminster Hall, the oldest existing part of the Palace of Westminster, was erected in 1097, at which point it was the largest hall in Europe. The hall has the largest clearspan medieval roof in England, measuring 20.7 by 73.2 meters (68 by 250 ft), and it is one of the most imposing medieval halls in Europe. Entrance to Westminster Hall is permitted only as part of a guided tour, otherwise it can be viewed from St. Stephen's porch above.