at this point we all agree anything to do with "United Nations" is evil and not to be trusted. Well they have a sister organization called United Nations Educational, Scientific and Cultural Organization (UNESCO) - https://en.wikipedia.org/wiki/UNESCO

They got a HUGE list and map of famous places of great historical interest (some ancient, some well known, many obscure) and some of these places are completely controlled and cut off from the public study. - https://whc.unesco.org/en/list/

I spent like 20 mins just going thru a few that caught my eye and heres 2 things iv found.

Ħal Saflieni Hypogeum - a huge underground labyrinth right in the middle of a city. Its something like 7000 years old... oh and they might have found elongated skulls there from a lost race... I shit you not.

then there this huge lake in Russia called lake baikil. Bigger then all the great lakes and insanely deep. Theres some weird myths about that place, rumors of UFOs and underwater/ground civilizations ect. Russia built a giant neutrino telescope right in the middle of it.

people interested in DUMBs, ancient history or underground labyrinths will love this shit.