class
From Underfoot
Classes
coastal cave - slate mine - small-scale coal mine - spiral tunnel - tik-kuyu - tramway tunnel - underground bicycle parking - underground mine - summit tunnel - cave with prehistoric art - silver mine - pylon station - rock-cut tomb - rock temple - sea cave - sommerkeller - volcanic pipe - zemlyanka - railway station underpass - immersed tube - blast-hole - burraia - chromium mine - double shaft mine - drainage tunnel - glacier tunnel - gravel pit - helical tunnel - bauxite mine - iron mine - mercury mine - military tunnel - mine shaft - oil mine - opencast mine - pit quarry - rare earth mine