Catacomb
An underground system of tunnels and chambers with recesses for graves, used (in former times) as a cemetery; a subterranean tunnel system used for burying the dead, as in Paris or Ancient Rome. (source)
An underground system of tunnels and chambers with recesses for graves, used (in former times) as a cemetery; a subterranean tunnel system used for burying the dead, as in Paris or Ancient Rome. (source)