Tongue: The Mouth of Vlad

It doesn't have to have that exact name, but the vampires should have a sufficiently creepy-sounding entrance to their "secret" lair. The Tongue of "whoever founded this exactly clan of vampires" would be sufficiently oddball.
It leads deep into the ground, and after years of effort, it does look like a mouth with a tongue but somehow in a natural way where it seems like the rock just looks like that. Enough to explain the name without having a lot of spelunkers find it terribly interesting. Also a lot of cave seekers have gone missing over the years so most people just avoid the area.