St Paul's Cathedral familiar with the unique octagonal lantern tower over the crossing of Ely Cathedral, which spans the aisles as well as the central nave, unlike the central towers and domes of most churches. Wren adapted this characteristic in designing the dome of St Paul's. In section St Paul's also maintains a medieval form, having the aisles much lower than the nave, and a defined clerestory. The most notable exterior feature is the dome, which rises to the cross at its summit, and dominates views of the City. The height of 365 feet is explained by Wren's interest in astronomy. Until the
Chichester Cathedral the free-standing bell-tower of the early 15th century, probably the work of William Wynford who also designed the cloisters, with openings in the Perpendicular style. St Mary's Almshouses in Chichester, which are linked to the cathedral, are a Christian charity dating from the 13th century. The medieval Hospital, associated with the Alms House, is one of only two such buildings in the world, the other being in Germany. The cathedral has many treasures and artworks, the most precious being two carved reliefs dating from the 12th century which are of exceptional rarity among English sculpture. Other ancient treasures include the