This is the Presbytery of Reppel, and the former Abbey of the Norbertine (an order of the Roman Catholic Church). It dates back to 1600. It's where a priest lived and collected tithes from the parish. The moat around the Presbytery isn't large enough to provide much protection, but it's connected to a stream and believed to be the home of fresh fish that were a part of the priest's diet. There was also a vegetable garden and small orchard on the property. Times were tough, and there wasn't much to eat in this area. 
A Presbytery usually consisted of a rectangular building and one or two barns. Tithings were normally in the form of harvested crops, and they had to be stored somewhere. That was the other reason for the moat. A place with so many valuable goods stored needed some form of protection. Take notes. This might be a question on Jeopardy one day and you'll thank me.
