Vault-like

Rodrigo opened a vault-like door.

Source: tatoeba (11785546)

Thus furniſhed with the means of finding their way, they deſcended to the kitchen, an immenſe vault-like room, where the almoſt famiſhed wretch, fortunately, found enough to appeaſe the hunger that devoured him: […]

Source: wiktionary

The cellar was a vault-like dungeon of a place, built solidly of brick, with only a narrow, barred window and the door from the kitchen opening into it.

Source: wiktionary

The up and down lines ran next to each other in vault-like tunnels, whereas the Tube trains would occupy their own tunnels.

Source: wiktionary