The underground world of Earth has not been studied in the best way, to say the least.
For example, on old maps, there is a legendary underground city of Grustina. Even 300-500 years ago, he was part of Tartary and connected the neighboring cities by underground tunnels. The city was under modern-day Tomsk, where even now the underground passages and exits to the surface are known to many local residents.
It is interesting that the city is on many European maps, information about it can be found in the memoirs of merchants, monks, travelers who at different times visited Russia. In Russian literature, however, mentions of such a marvel of architecture are destroyed, and remain in the works of Karamzin and Kluchevsky.
