In 612 the Irish monk Gallus withdrew to a wooded valley near Lake Constance. In 719 Otmar founded a Benedictine abbey on the site of his hermitage, which in the following centuries became one of the great centres of learning, writing and music in medieval Europe.
The abbey holds the Plan of St Gall, drawn around 820: the oldest architectural plan of the medieval West, with the church, cloister, gardens and workshops of an ideal monastery. The abbey and its library have been a UNESCO World Heritage Site since 1983.