Waxholm Fortress is located on the island of Kastellet at the entrance to Stockholm and has been a central part of the capital's defense for over 450 years. The facility began to be built in the 16th century during the time of Gustav Vasa, when the need to control the sea route to Stockholm became increasingly important.

The current fortress largely took its shape during the 19th century when it was remodeled into a modern artillery fort with thick walls, casemates, and cannon batteries aimed at the shipping lane. Vaxholm Fortress long served as a so-called lock fortress – a point where enemy ships could be effectively stopped.

Despite this, no live shots were ever fired in combat from the facility. During the 20th century, its military significance decreased, and in 1935 it ceased to be an active defense facility. Today, the fortress houses an outdoor toilet, a museum, a hostel, and exhibitions that tell about Sweden's coastal defense, the history of the archipelago, and the lives of the soldiers who served there.