Tower of London stands on the site of an earlier Norman stronghold, founded by William the Conqueror. Built in the south-east corner of the Roman town of Londinium, Gundulf, Bishop of Rochester supervised the replacement of this early fortification in the 1070s. Protected by the Roman town walls and to the north and west, a ditched earthwork bank crowned by a wooden palisade, the stone White Tower, of two storeys and basement was completed by 1100. The castle was then expanded almost continually through the centuries and it was King Edward I who founded the now world famous concentric stone palace-fortress and prison. The tower stands in the middle of the mid 13th century inner bailey curtain wall, which is flanked by thirteen round towers. The late 13th century outer bailey curtain wall, is flanked by six towers, a complex water-gate, two round-towered gatehouses, a D-shaped barbican and a large brick Bulwark. Legge's Mount and Brass Mount on the northern outer curtain wall are early artillery angle bastions and beyond the moat are parts of the medieval town wall. 8 miles south-east is Eltham Palace and 15 miles south-west is Hampton Court Palace.