Schloss Wartensee, Medieval château in Rorschacherberg, Switzerland

Schloss Wartensee is a castle complex in Rorschacherberg above Lake Constance, not to be confused with nearby Schloss Wartegg. Its west tower, built in 1243 as a residential tower by knight Heinrich von Wartensee, forms the oldest part; the Blarer family enlarged it into a triple residence, and the neo-Gothic remodelling of 1843–1853 by the son of composer Robert Lucas Pearsall gave it its present appearance and surrounding park.

The west tower was built in 1243 by knight Heinrich von Wartensee as a residential tower. Through marriage it passed in 1377 to the brothers Walter and Diethelm Blarer of St. Gallen, whose family owned it until 1719 and enlarged it into a triple residence. In 1757 the Segesser heirs sold it to the Abbey of St. Gallen for 12,000 guilders. Between 1843 and 1853 the son of English composer Robert Lucas Pearsall gave it its neo-Gothic appearance and surrounding park.

The name comes from the Wartensee family, whose knight Heinrich von Wartensee built the western tower in 1243. From 1377 to 1719 the Blarer family of St. Gallen owned the castle and expanded it into a triple residence. The neo-Gothic look and park date from the Pearsall family's rebuilding of 1843–1853.

The castle has operated as Schloss-Hotel Wartensee since 2013 under private ownership. It sits in Rorschacherberg above Lake Constance, and the grounds include a park laid out in the mid-19th century. The building is not to be confused with Schloss Wartegg in the same municipality.

The west tower, built in 1243 by Knight Heinrich von Wartensee, is the oldest part of the complex. The neo-Gothic appearance and the surrounding park date from the rebuilding by the son of English composer Robert Lucas Pearsall between 1843 and 1853. The castle is not to be confused with Schloss Wartegg in the same municipality.