The Mediaeval Hall
William I, having established his first stronghold at the Tower, later moved to Westminster; and it is from the reign of his son, William Rufus, that the first extant buildings on the site date, including Westminster Hall, the Great Hall, which was built at the northern end of the Palace and still stands today after celebrating nine hundred years of continuous use in 1999.
The hall was designed originally as a place for feasting and entertaining, but its very size made it more than that. Among other uses, the Royal Council of bishops, nobles and ministers assembled there. The special later form of this Council, which came to be known as Parliament, was the forerunner of the present House of Lords. It was also the site of the first true English parliament to include elected representatives, summoned by Simon de Montfort in 1265. While Parliament has never met in the Hall on a regular basis, it was the existence of the Hall, which at that time was the largest in Europe, that helped to make Westminster the judicial and administrative centre of the kingdom.
The Palace was one of the monarch's principal homes throughout the later Middle Ages, and for this reason the institutions of Government came to be clustered in the Westminster area. To the east and south of the Hall lay the domestic apartments of the mediaeval Palace, and later, the royal chapel of St Stephen. Kings worshipped in the upper Chapel and their courtiers in the lower level or "crypt" chapel below.
The Hall, of which the walls were built in 1097-99, as part of an intended reconstruction of the whole palace, is the oldest extant building on the Palace of Westminster site. Its floor area is about 1850 sq yds, and it is one of the largest mediaeval halls in Europe with an unsupported roof. The roof was originally supported by two rows of pillars, but the present magnificent hammerbeam roof was designed in the reign of Richard II. The mason/architect of the 14th century rebuilding was Henry Yevele, and the carpenter/designer of the roof, Hugh Herland. Westminster Hall was the traditional venue for Coronation banquets.
The Hall and the Law
During later centuries, the Hall housed the courts of law, and was the place of many notable state trials, for instance, those of Thomas More, Charles I, Warren Hastings, and the Gunpowder Plot conspirators. With its many shops and stalls, selling wigs, pens, books and other legal paraphernalia, it became one of the chief centres of London life.
The Hall, which survived the fire of 1834 and the bombing of 1941, is now used for major public ceremonies. Among recent events there have been the presentation of Addresses to the Queen on the Silver Jubilee in 1977, to mark 50 years since the end of World War II in 1995, and the opening of the Commonwealth Parliamentary Conference in 1986. A similar event took place in 1988, to mark the tercentenary of the Glorious Revolution, and in 1989 the Inter-Parliamentary Union's Centenary Conference was held there. In 1995 the Government organised a ceremony to mark 50 years of the United Nations. On these occasions, the Hall is brightly lit and decked with flowers and coloured hangings, and presents an altogether different public face from its normal rather sombre appearance. Distinguished heads of state sometimes address both Houses of Parliament there, as did President Mandela in 1996.
The Hall is also the place where lyings in state, of monarchs, consorts, and, rarely, very distinguished statesmen, take place. The first such occasion was Gladstone in 1898, followed by, in the last century, King George VI , Queen Mary  and Sir Winston Churchill . In April 2002 several hundred thousand people queued to pay their respects to Queen Elizabeth, the late Queen Mother, as she lay in state in the Hall.