English: 16th century oven with tiles showing biblical scenes, found in the cloister excavations.

Altenburg Abbey (Stift Altenburg) near Horn in the Waldviertel is a Benedictine Abbey founded in 1144 by Countess Hildeburg of Boigen-Rebgau. It was badly damaged by Swedish Forces in 1645 and was subsequently re-built in the Baroque style under the abbots Maurus Boxler and Placidus. The main architect was Josef Munggenast; artists and craftsmen of Austria who worked on this project include Paul Troger on the frescoes, Franz Josef Holzinger on the stucco work, and Johann Georg Hoppl on the carved marblework.

Emperor Joseph II in 1793 forbid the abbey to accept new novices, but unlike many others in Austria, it succeeded in remaining in operation. In 1940 under the Nazis the abbey was suspended, and in 1941 dissolved: the abbot was placed under arrest and the community dispossessed. From 1945 the premises were used as accommodation by Russian occupying troops. Under Abbot Maurus Knappek (1947–1968) the buildings were restored and the community renewed. During this period extensive archaeological excavation took place, revealing evidence for the original 12th century Romanesque Abbey and the Gothic re-modelling of the Cloisters.