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
Octagonal number Octagonal number An octagonal number is a figurate number that represents an octagon. The octagonal number for "n" is given by the formula 3"n" - 2"n", with "n" > 0. The first few octagonal numbers are: 1, 8, 21, 40, 65, 96, 133, 176, 225, 280, 341, 408, 481, 560, 645, 736, 833, 936 Octagonal numbers can be formed by placing triangular numbers on the four sides of a square. To put it algebraically, the "n"-th octagonal number is The octagonal number for "n" can also be calculated by adding the square of "n" to twice the ("n - 1")th