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
Elgin Cathedral tower in 1711. Elgin Cathedral is unique in Scotland in having an English style octagonal chapterhouse and French-influenced double aisles along each side of the nave; in England, only Chichester Cathedral has similar aisles. The chapterhouse, which had been attached to the choir through a short vaulted vestry, required substantial modifications and was now provided with a vaulted roof supported by a single pillar (Figs. 13 & 14). The chapterhouse measures high at its apex and from wall to opposite wall; it was substantially rebuilt by Bishop Andrew Stewart (1482–1501), whose coat of arms is placed on the central pillar.