Тайны затерянных подземелий

Medieval cities and fortresses, castles and monasteries were unthinkable without underground caches. They arranged passages for sorties and hidden water intake, for communication between various buildings of the defensive structure. The latter was protected from undermining by special structures, "rumors" - underground chambers or galleries. Where, by whom and how were underground caches built? How were they used? What structures are still hiding underground on the territory of Russia, Ukraine and Belarus?
In her book, Taisiya Belousova, a well-known journalist from the Sovershenno Sekretno newspaper, who specializes in investigating the most mysterious cases, tried to answer these questions. She looked for answers in chronicles and ancient documents, in legends and traditions, in the archives of historians and archaeologists, in the testimonies of pre-revolutionary and modern eyewitnesses and researchers.