Here you find a lot of cave elements which youcan use to construct your own dungeon. All materials are PBR, all textures size is 2048x2048.
Triangles count (by asset groups):
Walls elements - 22100 tris
Ceiling elements - 8250 tris
Floor elements - 9800 tris
Stalactites - 3700 tris
Stalactite strips - 1600 tris
Stalagmites - 9800 tris
Little stalagmites - 390 tris