Hammeren (also Hammerknuden; meaning, "hammerhead-shaped crag of granite")[1] is a protected area[2] and promontory in Denmark on the northernmost point of Bornholm island.

[4] The area includes Hammersø, the largest lake on the island and the only tarn in Denmark,[5] and a hill, 276 feet (84 m) in height, named Stejlebjerg (or Stieleberg).

It covers a rocky area of granite formations (considered one of the best examples of the kind)[8] extending over 182 hectares (450 acres) and including a number of caves.

Hammeren features a large lake, Hammersø, the largest on the island, and a deep pond, Opalsø, surrounded by the rocky slopes of a former granite quarry.

The chapel was constructed in connection with Bornholm's herring trade with the Hanseatic cities of Hamburg and Lübeck from the thirteenth to fifteenth centuries.