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
Bosa Cathedral single nave with a barrel-vaulted roof subdivided into five spans by pilasters and arches, with four side-chapels. The first chapel to the right is the great chapel ("cappellone") of the Sacred Heart, very elongated and arranged like a miniature church in itself, mirroring the cathedral in which it is set: the end part contains four little side chapels and a larger chapel under an octagonal cupola. The archway leading to the presbytery is narrower than the nave and flanked by two pilasters. The presbytery itself, which is very deep, is covered by an octagonal cupola (planned in the opening years