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
Mainz Cathedral appearance of the Salian western end is not known. In 1100, Henry IV ordered reconstruction in the old Lombardic style. The old flat chancel end on the east side was replaced with a large apse, which external gallery with a narrow arcade supported by short columns crowned the semicircular wall with a wide pseudo arcade and tall pillasters on both sides. The new chancel had a triple-nave crypt. The damaged square tower had been replaced with an octagonal dome, above which an octagonal tower was added later. Flanking stair turrets remained from the first cathedral. These changes closely resembled the