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
Asti Cathedral series of earlier buildings including a primitive church built on the crypt of the martyred saint, Secundus of Asti. Among other of these buildings still apparent is St. John's Church, used today for baptisms. Around 1070, the building collapsed, partly as a result of a fire that set by Adelaide of Susa in her dispute with the bishops. In 1095 the rebuilt Cathedral was consecrated by Pope Urban II to preach the first crusade. The bell tower was rebuilt starting in 1266 by the magister Murator Jacopo Ghigo consisting of seven floors, plus an octagonal spire, and it is visible