Over the three centuries of its existence, Nevyansk has kept many old secrets. One of them involves the dungeons on the territory of the Demidov plant. Local historians and researchers have made numerous attempts to lift the veil over this mystery.
The presence of underground structures on the territory of the Nevyansk plant is confirmed by eyewitness reports. Some of the basements were discovered due to accidental sinkholes, for example after a major fire in 1890. The rooms in the basement were repeatedly discovered during the plant reconstruction works — the construction of foundations, the laying of communications and other excavation work.
The most detailed studies were carried out in the 1970s–1990s by researchers at the Ural Academy of Architecture and Art (currently the Ural State University of Architecture and Art). The research was supervised by Professor Albert Eduardovich Korotkovsky and Professor Vsevolod Mikhailovich Slukin. The specialists searched and examined underground structures using geophysical methods. By recording local changes in physical fields in the ground, these methods make it possible to identify an object, its location, approximate size and shape, and the depth of its location.
As a result, researchers identified basement rooms with different functions. They included old facilities (drainage, ventilation) and various underground tunnels, passages, and rooms for non-technological purposes.
The dimensions of the underground spaces vary. For example, the basements are approximately five by seven meters and have cross or barrel vaults. There are underground passages with a cross section measuring 1.5×2 meters at a depth of three to four meters below the surface. The diameter of wooden pipes does not exceed half a meter.
It is noteworthy that the cellars under the Demidov Leaning Tower of Nevyansk, which are mentioned in folk legends, have not been discovered.
Based on the results of geophysical work, the researchers drew up a preliminary layout of the underground structures of the Nevyansk plant. They emphasized that both above- and underground monuments of the Demidov era have great historical, cultural, and artistic significance.
