Westminster is an area of the City of Westminster in London. It extends from the River Thames to Oxford Street, and has many famous landmarks, including the Palace of Westminster, Buckingham Palace, Westminster Abbey, Westminster Cathedral, Trafalgar Square and much of the West End cultural centre including the entertainment precinct of West End Theatre.
The name (Westmynstre) originated from the informal description of the abbey church and royal peculiar of St Peter's (Westminster Abbey), west of the City of London (until the English Reformation there was also an Eastminster, near the Tower of London, in the East End of London). The abbey's origins date from between the 7th and 10th centuries, but it rose to national prominence when rebuilt by Edward the Confessor in the 11th century. Westminster has been the home of England's government since about 1200, and from 1707 the Government of the United Kingdom. In 1539, it became a city.
Westminster is often used as a metonym to refer to the Parliament of the United Kingdom, in the Palace of Westminster.
The City and Liberty of Westminster and other historical Westminster administrative units (except the broader modern City of Westminster, a London Borough created in 1965) extended from the River Thames to the old Roman road from the City to western England, which is now locally called Oxford Street.
Thorney Island lay between the arms of the former River Tyburn at its confluence with the Thames, while the western boundary with Chelsea was formed by the similarly lost River Westbourne. The line of the river still forms (with very slight revisions) the boundaries of the modern borough with the Royal Borough of Kensington and Chelsea.
Further north, away from the river mouth, Westminster included land on both sides of the Westbourne, notably Knightsbridge (including the parts of Hyde Park west of the Serpentine lake (originally formed by damming the river) and most of Kensington Gardens).