It is often said that Florence's Cathedral is turned inside out: Its white, green and pink marble exterior boasts the famous dome and bell tower, while its interior is spare and almost barren. Florence’s distinctive Santa Maria del Fiore Cathedral, or Duomo, is the result of six centuries of work. The city hired Arnolfo di Cambio to design a new Duomo to replace the tiny 6th century Santa Reparata in 1296 and numerous local artists continued to work on it during the following century and a half. The painter Giotto designed its sturdy bell tower (Campanile) in 1334. The massive octagonal cupola that dominates both the church and the city was the proud achievement of master architect and sculptor Filippo Brunelleschi in the 15th century, who ingeniously designed it to support itself both during and after its construction, while the neo-Gothic façade that completed it was completed in the late 19th century. Gaddo Gaddi was commissioned to mosaic an Enthronement of Mary in the lunette above the inside of the main door and Lorenzo Ghiberti designed the stained-glass windows set in the facade. Paolo Uccello, a painter obsessed by the newly developed perspective, frescoed the huge hora italica clock with its four heads of Prophets in 1443. The frescoes on the interior of the dome were designed by Giorgio Vasari but painted mostly by his less-talented student Frederico Zuccari by 1579. Climb up the 414 steps between the two shells of the cupola for one of the classic panoramas of the city.