The remains of the Castle can be visited
Cloppenburg Castle

The remains of Cloppenburg Castle are the preserved ruins of a medieval defensive structure in the city of Cloppenburg. It was once built to secure regional sovereignty.
History+
The construction of Cloppenburg Castle dates back to Count Otto III of Tecklenburg, who around 1297 had a fortification built near the settlement of Krapendorf in a Soeste lowland. The first documented mention can be found in a document from January 5, 1297. After an alliance was formed between the bishops of Münster and Osnabrück and the cities of Münster and Osnabrück in 1393, the castle was conquered in the same year. It came into the possession of Bishop Otto IV of Hoya from Münster in 1396, after the Bishop of Osnabrück had ceded his share. Count Nikolaus II of Tecklenburg renounced his claims in 1400.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://de.wikipedia.org/wiki/Datei:Cloppenburg_castle.jpg
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 52.8471, 8.0451