Radzyń Chełmiński Castle - Credit: Wikimedia Commons
Radzyń Chełmiński Castle is a Brick Gothic monastery-castle completed in 1330 as the seat of the Teutonic Knights' Commandry. It lies near Castle Lake (Polish: Jezioro Zamkowe) to the north of the town of Radzyń Chełmiński. Three of the four walls and most of the internal buildings of the keep are ruined. Read more on Wikipedia
Source: en.wikipedia.org