Westminster Hall

The oldest extant part of the Palace of Westminster, Westminster Hall was built in 1097 and was, at the time, Europe’s largest hall. For centuries, it served as the legal and administrative center of the country and has also been the venue for coronation banquets, medieval feasts and celebrations, and grand political displays. Its name is derived from the neighbouring Westminster Abbey,The first royal palace was built on the site in the 11th century, and Westminster was the primary residence of the Kings of England until fire destroyed much of the complex in 1512. After that, it served as the home of the Parliament of England, which had been meeting there since the 13th century,

The Palace of Westminster is the meeting place of the House of Commons and the House of Lords, the two houses of the Parliament of the United Kingdom. 
The Palace of Westminster has three main towers. Of these, the largest and tallest is 98.5-metre (323 ft)^[41] Victoria Tower, which occupies the south-western corner of the Palace.The shortest of the Palace's three principal towers (at 91 metres (299 ft)^[41]), the octagonal Central Tower stands over the middle of the building, immediately above the Central Lobby.At the north end of the Palace rises the most famous of the towers, Elizabeth Tower, commonly known as Big Ben.
The Palace of Westminster contains over 1,100 rooms, 100 staircases and 4.8 kilometres (3 mi) of passageways
https://www.parliament.uk/visiting/online-tours/virtualtours/westminster-hall-tours/westminster-hall-3d/