The Duomo, Milan's cathedral, is one of the largest churches in the world; is a surprisingly elegant mass of marble boasting 135 spires and 3,400 statues. Commissioned in 1386, by Gian Galeazzo Visconti, the Duomo was not finished until the early 1800s. The building began life as a Gothic cathedral, but over the centuries the designs went through several modifications, and the finished Duomo is a strange mixture of styles.