Its name, which is derived from the neighbouring Westminster Abbey, may refer to either of two structures: the Old Palace, a medieval building complex destroyed by fire in 1834, and its replacement, the New Palace that stands today. The palace is owned by the monarch in right of the Crown and for ceremonial purposes, retains its original status as a royal residence. The building is managed by committees appointed by both houses, which report to the Speaker of the House of Commons and the Lord Speaker.
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, and also as the seat of the Royal Courts of Justice, based in and around Westminster Hall. In 1834, an even greater fire ravaged the heavily rebuilt Houses of Parliament, and the only significant medieval structures to survive were Westminster Hall, the Cloisters of St Stephen's, the Chapel of St Mary Undercroft, and the Jewel Tower.
The subsequent competition for the reconstruction of the Palace was won by the architect Charles Barry, whose design was for new buildings in the Gothic Revival style, specifically inspired by the English Perpendicular Gothic style of the 14th–16th centuries. The remains of the Old Palace (except the detached Jewel Tower) were incorporated into its much larger replacement, which contains over 1,100 rooms organised symmetrically around two series of courtyards and has a floor area of 112,476 m2 (1,210,680 sq ft). Part of the New Palace's area of 3.24 hectares (8 acres) was reclaimed from the River Thames, which is the setting of its nearly 300-metre long (980 ft) façade, called the River Front. Barry was assisted by Augustus Pugin, a leading authority on Gothic architecture and style, who designed the interior of the Palace. Construction started in 1840 and lasted for 30 years, suffering great delays and cost overruns, as well as the death of both leading architects; works for the interior decoration continued intermittently well into the 20th century. Major conservation work has been carried out since then to reverse the effects of London's air pollution, and extensive repairs took place after the Second World War, including the reconstruction of the Commons Chamber following its bombing in 1941.
The Palace is one of the centres of political life in the United Kingdom; "Westminster" has become a metonym for the UK Parliament, and the Westminster system of government has taken its name after it. The Elizabeth Tower, in particular, which is often referred to by the name of its main bell, Big Ben, is an iconic landmark of London and the United Kingdom in general, one of the most popular tourist attractions in the city, and an emblem of parliamentary democracy. The Palace of Westminster has been a Grade I listed building since 1970 and part of a UNESCO World Heritage Site since 1987.
The Palace of Westminster site was strategically important during the Middle Ages, as it was located on the banks of the River Thames. Known in medieval times as Thorney Island, the site may have been first-used for a royal residence by Canute the Great during his reign from 1016 to 1035. St Edward the Confessor, the penultimate Anglo-Saxon monarch of England, built a royal palace on Thorney Island just west of the City of London at about the same time as he built Westminster Abbey (1045–50). Thorney Island and the surrounding area soon became known as Westminster (a contraction of the words West Minster). Neither the buildings used by the Anglo-Saxons nor those used by William I survive. The oldest existing part of the Palace (Westminster Hall) dates from the reign of William I's successor, King William II.