The construction of the cathedral was commissioned by bishop Antonio da Saluzzo in 1385. He was supported by the first duke of Milan, Gian Galeazzo Visconti, who envisioned the creation of the world's largest church. He gave access to his marble quarries, granted tax exemptions and invited architects from across Europe. Construction commenced in 1386, but it would drag on for centuries. When the cathedral was consecrated in 1418, construction of the nave had only just started. Construction would continue until 1813, and final finishes were applied as late as in 1965.
Over the years numerous master builders were involved and the initial design was continuously altered to become even more spectacular. The long construction period also led to a mash-up of a variety of styles but the final result is surprisingly homogenous, with a decidedly flamboyant Gothic design.