The Rotunda of St. Catherine (Czech: Rotunda sv. Kate?iny), known as the Znojmo Rotunda (Znojemská rotunda), is a Romanesque rotunda located in Znojmo, Czech Republic. It is the town's most valuable monument, and features one of the oldest fresco compositions in the Czech lands. Besides the religious motives, of particular importance is the praising portrayal of the ruling P?emyslid dynasty.
The building was originally a castle chapel, dedicated to Virgin Mary, built in the mid-11th century. The painting was commissioned by Konrad II of Znojmo on the occasion of his wedding with Mary (Marija), daughter of Uro? I of Serbia in 1134. Apart of the donor couple, Konrad and Mary, the identity of the other depicted members of the dynasty is disputed among the historians. With two exceptions being the P?emysl the Ploughman, the legendary ancestor of the dynasty, and Vratislaus I, the first King of Bohemia.