Underground vaults (6)
I believe the answer is:
crypts
(Other definitions for crypts that I've seen before include "Vaults, mausoleums" , "Underground burial chambers" , "Vaults and tombs" , "Vaults used as burial places" .)
I believe the answer is:
crypts
(Other definitions for crypts that I've seen before include "Vaults, mausoleums" , "Underground burial chambers" , "Vaults and tombs" , "Vaults used as burial places" .)