In the Middle Ages, the site of the future palace formed part of the Manor of Ebury (also called Eia). The marshy ground was watered by the river Tyburn, which still flows below the courtyard and south wing of the palace. Where the river was fordable (at Cow Ford), the village of Eye Cross grew. Ownership of the site changed hands many times; owners included Edward the Confessor and his queen consort Edith of Wessex in late Saxon times, and, after the Norman Conquest, William the Conqueror. William gave the site to Geoffrey de Mandeville, who bequeathed it to the monks of Westminster Abbey.

Which river runs underneath the palace?