On Wednesday, HS Helsinki told about an underground tunnel found under Telakkakatu in Punavuori, the history and purpose of which no one seemed to know.

HS readers eagerly set out to find out and found a solution in the city’s databases. From there, it becomes clear that this is a light gap running almost entirely around the building and then a technology channel.

The red-brick building in the Maritime Quarter was granted a building permit in 1919. At that time, a light shaft was also built in the basement floor, with window openings visible at street level. The purpose of this lighting corridor was therefore to direct natural light into the basement.

In the facade plan of Telakakatu in the Maritime Quarter from 1919, you can see the tops of the windows in the basement near the land border.

Photo: City of Helsinki building drawing service Arska

At some point, however, the windows were bricked up and a technical canal was built next to the wall. However, it is not clear from the old building drawings why and when the change was made. Some readers recalled that the windows on the Telakkakatu side would have been bricked up in the 1960s or 1970s.

According to Erkki Hassinen, the inspection engineer of the City of Helsinki, there may have been many reasons. The windows may have become a nuisance once water has entered the basement and the plumes have been filled with snow in the winter.

The narrow corridor-like layer is tens of meters long.

Photo: Tuukka Lehto / VM Suomalainen

The light gap runs along the edges of the basement. Building drawing from 1937.

Photo: City of Helsinki building drawing service Arska

Over the years, the street and sidewalk have been raised several times, leaving the windows hidden underground. The street interest rate may have been raised for the first time decades ago, which is why the windows had to be closed.

“Probably in connection with some water and sewer repairs, it has been decided to utilize the space as a technical space,” says Hassinen.

"Unfortunately, this was no more bizarre mystery now."