Norwich Castle is an 11th century earthwork motte and baileys fortress, founded by King William I. Early in the 12th century, King Henry I founded the stone castle, when adding a huge ornate keep, to the enormous motte. In the early 13th century, drum towers and a gatehouse were added, with a drawbridge and a stone bridge spanning the dry ditch. The baileys, to the south and north-east, were encased by ramparts and ditches and one had an inner barbican but sadly they have been built over and little now remains. In 1824, Anthony Salvin restored the interior of the keep and refaced its exterior, reproducing the original blank arcading. The forebuilding, a Victorian restoration, leads to the Bigod Arch, which is original entrance to the Royal Palace. 5 miles north is Horsford Castle.