The ruins of Stjärnorp castle are situated just north of Bergs slussar, with stunning views of Lake Roxen. The castle was built by count Robert Douglas and designed by architect Nicodemus Tessin the elder, also famous for designing the castle of Drottningholm.
A great fire destroyed the castle in 1789 and today visitors can only access the outside of the castle ruins. The church of Stjärnorp, located in the east wing is open to the public.
In the ravine, just next to the ruins, is a lovely hiking trail along a stream. In the springtime the ravine is full of bracken ferns.