Construction of the campanile of the Cathedral of Pisa (now known as the Leaning Tower of Pisa) begins; it will take two centuries to complete.

A bell tower is a tower that contains one or more bells, or that is designed to hold bells even if it has none. Such a tower commonly serves as part of a Christian church, and will contain church bells, but there are also many secular bell towers, often part of a municipal building, an educational establishment, or a tower built specifically to house a carillon. Church bell towers often incorporate clocks, and secular towers usually do, as a public service.

Pisa Cathedral, officially the Primatial Metropolitan Cathedral of the Assumption of Mary, is a medieval Catholic cathedral dedicated to the Assumption of the Virgin Mary, in the Piazza dei Miracoli in Pisa, Italy, the oldest of the three structures in the plaza followed by the Pisa Baptistry and the Campanile known as the Leaning Tower of Pisa. The cathedral is a notable example of Romanesque architecture, in particular the style known as Pisan Romanesque. Consecrated in 1118, it is the seat of the Archbishop of Pisa. Construction began in 1064 and was completed in 1092. Additional enlargements and a new façade were built in the 12th century and the roof was replaced after damage from a fire in 1595.

The Leaning Tower of Pisa, or simply the Tower of Pisa, is the campanile, or freestanding bell tower, of Pisa Cathedral. It is known for its nearly four-degree lean, the result of an unstable foundation. The tower is one of three structures in Pisa's Cathedral Square, which includes the cathedral and Pisa Baptistry. Over time, the tower has become one of the most visited tourist attractions in the world as well as an architectural icon of Italy, receiving over 5 million visitors each year.