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
Truro Cathedral work on the central tower and spire has begun. Restoration work is being carried out by W. R. Bedford; Stuart Aston, managing director, said that the problem is the Bath Stone used on the more decorative areas of the cathedral, has not stood up well to the salts and sand in the maritime climate of Cornwall. Erosion of the stonework has left much of the exposed stonework in such a damaged condition that it resembles honeycomb. Funding for the restoration of the tower and spire has been partly met by grants from English Heritage, Friends of Truro Cathedral, the Heritage