The historic City of Londonderry straddles the river Foyle, the two parts are joined by the Craigavon road bridge and a new pedestrian peace bridge. Perhaps the most iconic feature of the city is the famous walls which were built between 1613-18. Today they surround the old part of the city which has some exceptional period architecture, within the walls is St. Columb's Cathedral named after Columb who founded a monastic settlement here known as Daire Calgach which became known as 'Daire Columcille'.