The chapel at Rønvik was completed in 1903, following two years of construction. It is built of timber materials and the constructive sections are used decoratively: amongst other things, the vertical load-bearing elements divide up the wall expanse both outside and in. The building has painstaking Swiss-style details with elements of dragon style, for example in the decorations on the small copper-clad ridge turret. The chapel may have been delivered as a prefabricated set from one of the contemporaneous firms supplying prefabricated housing in Trøndelag. The choir section was destroyed during the Second World War, when the site was requisitioned by the occupying power, and was built up again during the 1950s.

The new building for the Security Department was ready for use by 2009, a building that contains strong features of its own time, but at the same time its size, shape and use of materials are suited to the existing site.