A few years ago we were staying with friends in Koln to explore the Eifel region. It was too far to get to the west of the region and back in a day, so one of them arranged somewhere for us to stay over.
"It's very cheap but very clean" she said.
When we arrived, we found we were staying in a monastery! It was on the Santiago di Compostela pilgrimage route, so at each breakfast we were surrounded by eager pilgrims ready for the next stage.
I mention it becuase the extensive grounds were dominated by six very large fishponds - required for one of the day's food.
btw, did you know that the Eifel region is over a supervolcano, like Yellowstone? There's lots of evidence of activity - hot springs, etc. - and the whole lot may go off one day; yet another thing to worry about!