Kreuzlingen Abbey (Stift Kreuzlingen or Kloster Kreuzlingen), in Kreuzlingen in Switzerland, on the border with Germany, was founded in about 1125 by Ulrich I of Dillingen, Bishop of Constance, as a house of Augustinian Canons. In 1848 the government of the Canton of Thurgau dissolved the monastery and took over its property. The former abbey church of Saint Ulrich and Saint Afra, decorated in the Baroque style, is noteworthy.
Saint Conrad, Bishop of Constance from 935 to 976, brought back from Jerusalem a fragment of the True Cross, which he presented to the hospital he had founded in the suburb of Stadelhofen and from which it took the name of "Crucelin" which later became Crucelingen / Kreuzlingen. In 1093 this hospital was burnt down during hostilities between the Bishop of Constance and the Abbot of St. Gall.
Ulrich I, bishop of Constance from 1111 to 1127, restored the derelict hospital of Kreuzlingen in about 1125 by founding, on the eastern edge of the suburb of Stadelhofen, a house of Augustinian Canons (indeed, one of the earliest) dedicated to Saints Ulrich and Afra.
In 1144 Pope Lucius II, and in 1145 Emperor Frederick Barbarossa took the monastery under their protection. Kreuzlingen became an Imperial abbey. The abbots, now Imperial prelates, were territorial lords of the small lordship of Hirschlatt north of Friedrichshafen, and this was also their place of refuge in times of war.