After a fire in 1624 burned down a large portion of the town, the Danish-Norwegian King Christian IV, deciding to rebuild the town, supposedly pointed to this spot and said: "The new town will lie here!" A quaint square surrounded by cafes.
A great place to stop for a beer or coffee in the sun after walking around Akershus fortress. Also a stone's throw away from Rådhuset. In the summer it can get busy with tourists from the cruise ships, so be prepared for a crowd.
Earlier is better