Almost a kilometre of mutually perpendicular passages cut in the rock below Petrov. The system of vaulted passages, located in a rectangular area approximately 85 x 60 metres, provided shelter for up to three thousand people for four days in the event of an atomic explosion.

TEBRIX is a company that specializes in the design and construction of underground fallout shelters, the security of buildings (single-family homes, apartment buildings, schools, hospitals, and other commercial structures), underground shooting ranges, and the inspection and subsequent renovation of civil defense shelters.