A former Carthusian monastery on a hill above the Thur River, founded in 1461 and dissolved in 1848. The site is now a complex of museums, a working farm and restaurant, an art gallery, and a hotel. The Ittinger Museum covers eight centuries of Carthusian history and includes the original 18th-century church with its baroque choir stalls; the adjacent Kunstmuseum Thurgau holds the cantonal art collection in the converted dairy barns.
It is the single most rewarding visit in Thurgau. Allow most of a day: museum, monastery garden, lunch at the Mühle restaurant on the property (the kitchen uses ingredients from the farm), and the herb garden with around 200 medicinal plants. About 5 km north of Frauenfeld; reachable by bus 824 or a short drive.