Lubyanka (Moscow Metro)

Construction work on the station began in December 1933, and the engineers were faced with extremely difficult soil conditions from the outset.

It was quickly discovered, however, that the clay was much softer than anticipated due to the proximity of an underground channel of the Neglinnaya River and also tended to swell greatly when exposed to air.

This meant that the tunnels had to be built one section at a time, very quickly, in order to allow the concrete to set before the pressure exerted by the expanding clay increased to the point where the wooden forms could no longer contain it.

In 1965 it was revealed that Lubyanka was to become a transfer point to the planned Tagansko-Krasnopresnenskaya Line, making it clear that the station would need to be completed.

Technology had advanced to the point where the building of the central hall, which had been deemed impossible in the 1930s, could finally be accomplished, though this project still took more than seven years to complete.

Workers were forced to go back to the original method of quickly building one tunnel segment at a time before the expansion of the clay could crush them.

The distinctive facade, facing the Lubyanka square, with twin arches was designed by architect Iosif Loveyko, to remind the public of the historic Vladimir gates of the Kitay-gorod wall that was demolished a few years prior.

The 7 metre (23 ft) high smaller incline to the subterranean vestibule originally had three LP-6I escalators, but as this model proved troublesome after long use, it was prematurely replaced throughout the Metro during the 1990s.

In 2008 the Detsky Mir was closed for reconstruction, and the original building that the entrance was built into was demolished in 2010 and a Kempinski hotel is being erected in its place, though the ground floor and facade are retained.