Chillon Castle (French: Château de Chillon) is a castle located on the shore of Lake Léman, 3 km from Montreux, Switzerland. The castle consists of 100 independent buildings that have been linked to form a unified complex. It is considered one of the most beautiful castles in Europe because of its poetic beauty and is often visited by tourists when visiting Switzerland. Chillon is listed as "the most visited historical monument in Switzerland". The later history of Chillon is influenced by three main periods: the Savoy Period, the Bernese Period and the Vaudois Period. The oldest parts of the castle are undated, but the first written record of the castle dates to 1005. From the mid-12th century, the castle was the summer home of the Counts of Savoy, who kept a fleet of ships on Lake Geneva. The castle was rebuilt in the 13th century from an earlier castle and served as a medieval fortress to guard one of the main roads through St. Bernard, Italy and as a strategic position against invading forces by Pierre II of Savoy, designed by the architect Pierre Mainier. The castle is a complex of 25 buildings with nearly 100 buildings, 110m long and 50m wide at its widest point. During the Wars of Religion in the 16th century, it was used by the Dukes of Savoy to hold prisoners. Its most famous prisoner was probably François de Bonivard, a Genevois monk, prior of Saint Victor of Geneva and politician who was imprisoned there from 1530 to 1536 for defending his homeland from the Duke of Savoy. In 1816, the poet Lord Byron referred to the castle's prisoners in his poems (1816) in his composition The Prisoner of Chillon.