St Gall cathedral was built in 1755–1770 as the church of the Benedictine monastery, which was dissolved in 1805. In the Middle Ages this church, erected on the site of the hermitage of St Gallus, was one of the most important monasteries in the western world. Today the Abbey Archive and Abbey Library still possess invaluable documentary evidence from that era. The Baroque monastery complex testifies to the flourishing of the prince-abbey in the 17th and 18th centuries. The church, like the adjacent abbey library, built after the plans of Peter Thumb and decorated by the best South German artists of the day, forms the monumental conclusion of a long series of Baroque abbey churches realised by Vorarlberg master builders. St Gall's abbey district is a UNESCO World Heritage Site, the collections of the Abbey Library and Archive are included in the UNESCO World Documentary Heritage List.