Its most famous treasure is Mappa Mundi, a medieval map of the world created around 1300 by Richard of Holdingham.[2] The map is listed on the UNESCO Memory of the World Register.[2] The cathedral is a Grade I listed building.[3] The site of the cathedral became a place of worship in the 8th century or earlier although the oldest part of the current building, the bishop's chapel, dates to the 11th century.[2]