The tumultuous history of a women's convent in southern Lower Saxony as documented in primary sources. The history of the choir women's convent of Katlenburg, located on the western edge of the Harz Mountains, dates back to 1105. The childless Count Dietrich III of Katlenburg founded the monastery and used his own castle complex for its accommodation. Initially dedicated to Saint John, the convent transformed into an Augustinian monastery under Welf rule. From the 13th century until its secularization in 1534, the convent became a refuge for the daughters of the southern Lower Saxony nobility. Numerous raids and fires over the centuries have resulted in a challenging preservation situation for the choir women's convent of Katlenburg. The few surviving documents ended up in the hands of various Welf lines and finally reached the state archive in Hanover in 1721. The register of documents of August.