A few years ago, some people noticed 2 entrances on Google Maps which appear to lead underground, despite nothing being marked on the map there. Apparently, one of the entrances has now been "censored" by Google Maps (due to the censorship I was not able to confirm this independently), while the other is still there.
The one I was able to verify is located about 185 miles from the nearest station, which is Mirny Station (Russia). It seems to be a large tunnel leading underground, with a metal canopy positioned above it. It's located at GPS co-ordinates (-66.60350473548475, 99.719778).
The other one is located about 5 miles from the first, at GPS co-ordinates (-66.55337, 99.838783). Since it has supposedly been "censored" by Google Maps, only a green blob can be seen there. However some other (admittedly questionable) websites are carrying the image supposedly before it was censored. They show a similar tunnel, but without the metal canopy. Here is an example. Even assuming that is real, it's still far less interesting than the first one, which looks more likely to be man-made due to the metal canopy.
Can anyone find any logical explanations for what these might be, other than "evidence of alien invasion" or "a secret Nazi underground city", which seem to be two of the prevalent conspiracy theories (!)?