Kloster Haydau, Cistercian monastery in Morschen, Germany

Kloster Haydau is a former Cistercian nunnery in Altmorschen, a district of Morschen. Its early Gothic hall church, built around 1280 without a tower but with a roof turret, stands beside the south wing, whose Engelsaal above the former refectory has a painted ceiling of angels, clouds and flower garlands. The present buildings largely date from the 1616-1619 conversion into a hunting lodge.

Founded on 23 January 1235 by Hermann I of Treffurt as a Cistercian nunnery, after his brother Friedrich II did penance for the 1232 sack of Fritzlar. A fire during a Treffurt family feud destroyed it in 1319; it was rebuilt the next year. In 1527 the Reformation dissolved the monastery, which became a landgrave's hunting lodge.

The Engelsaal, created around 1600 under Landgrave Moritz of Hesse-Kassel above the former refectory in the south wing, has a painted ceiling of angels, clouds and flower garlands and a large fireplace. The monastery church became Protestant after the Reformation and served as the landgraves' court church, with wooden galleries added in the nave.

Kloster Haydau stands in Altmorschen, a district of Morschen in the Schwalm-Eder-Kreis. The former monastery church, now the Schlosskirche, keeps its early Gothic hall form without a tower; a bell turret was added around 1600. The Engelsaal lies above the former refectory in the south wing. The Herrenhaus, renovated from 1982, has served as Morschen's town hall.

The site ranks among the most complete Cistercian monastery structures in Hessen, having retained its original medieval architecture over centuries. This completeness makes it a rare example of how such communities were physically organized.