Here's one of the inside (through the barred doorway) of the Abbey ruins. From the tourist book:
These, one of the most beautiful church ruins in Germany, are situated in a beautiful small park and belonged to a former Augustinian monastery which was established by Count Bernard II and first mentioned in 1207. Particularly worth seeing are the high Gothic tracery windows and the refectroy with arches from the former cloister. The heart of the Lippian nobility lies here in the abbey and its surrounds.