The northern half of Stockholm is geographically dominated by the Brunkeberg ridge that goes in a north-south direction. Over the centuries it has been excavated for building materials or simply removed. However, back in 1884 it was thought that a tunnel through it would be economically feasible. The construction turned out to be difficult, since the ridge consists of stratified sand and gravel. By freezing the water content of the surrounding ridge, it could be excavated at a rate of 60-90 centimeters per day. After two years the tunnel was finished, but the citizens of Stockholm thought the fee of two öre to use it was too much. The interior view is east from approximately 20 meters in from the west entrance.