Introduction to the main church: The Cathedral (Duomo) is also known as the Duomo Cathedral. The foundation of the church was laid in 1296. The main body is 106 meters high. Its exterior is decorated with green, white and red marble, applying the principles of architecture and geometry. Design and build. The interior is relatively spacious. The west hall is about 80 meters long and divided into four rooms. The distance between the pillars is about 20 meters, and the span of the middle hall is also the same. Only the choir on the east side is special. It is octagonal, and the distance between opposite sides is equal to the width of the hall, about 42 meters. Due to technical problems, the dome on the choir was not built by geniuses until the first half of the 15th century. The architect Brunelleschi designed and built it in imitation of the Pantheon in Rome.