According to a defence decision of 1914, Vaxholm Fortress was to be reinforced by an outer line of defences consisting of forts and artillery batteries.
Siarö Fort was positioned in the busiest part of the channel from Finland. This place was at that time the most strategically important point in the sea approach to Stockholm.
Siarö Fort lay in wait to ambush the enemy. Any enemy fleet would be destroyed in an inferno of fire and smoke. The concrete crown of the fortress is supposed to resemble the natural terrain. All around the fortress is a barbed wire barrier.
As long ago as 1920 discussions began on the question of moving the coastal defences out to the outer edge of the archipelago, and back in 1939 Siarö Fort ceased operations in its original form. The cannon were removed in 1951, the mine battery was discontinued in 1959 and in 1960 all other materiel was removed from the fort.
Siarö Fort is now open to the general public. The interior of the fortress contains, among other things, living quarters, messes, kitchens, a command centre and magazine.
Large parts of the fort have been returned to their original condition, and in the main section, in addition to the authentic environments, there are also displays on Siarö Fort and the coastal defences.
On the island there is a café, a youth hostel for around 30 people, a conference room and berths for pleasure boats.
- Audio guide
- Guest harbour