As the name suggests, Långholmen is a long and narrow island. In older times, it consisted of lean pastures situated amongst bare rocks. On the island, there are traces of ancient dwellings dating back to the 10th century. In the 19th century, a silver hoard of German coins minted in the 10th century was found here. The island was first mentioned in historical documents in 1435. These medieval documents relate that Sweden’s Council of State held a meeting in Långholmen.