Fredriksborg Fortress is a fortification complex on Värmdö at Oxdjupet strategically placed at the entrance to Stockholm. The fortress and surrounding buildings were a crucial part of the defense infrastructure built in the Stockholm archipelago to protect Stockholm from Russian colonies along the east coast in 1719. The fortifications were completed in 1735 and are called Fredriksborg’s fortress after King Fredrik I and was considered to be Europe’s strongest fortress at the time. In 1724 the work of the fortress was based on a design written by General-Quartermaster Axel Löwen. Sitting atop a plateau, 40 meters above the water and equipped with a gun and cannon gallery, Fredriksborg was ready to protect Stockholm. The fortress is surrounded by a moat and could only be reached via a draw bridge whose machinery is still preserved in original condition.
Certain parts of the fortress are open to visitors during the summer months.