The Palace of Westminster at dusk, showing the Victoria Tower (left) and the Clock Tower colloquially known as 'Big Ben'. The palace lies on the bank of the River Thames in the heart of London. The oldest part, Westminster Hall, dates to 1097, but most of the present structure dates from the 19th century, when it was rebuilt after it was almost entirely destroyed by a fire in 1834. Together with Westminster Abbey and Saint Margaret's Church, the palace is listed as a UNESCO World Heritage Site.Photo credit: Diliff