Yes
During the creation of the bunker, they found Roman tunnels, and excavated them, looking for a potential way to flank the Germans
While they were excavating, people had nightmares and visions, and found from artifacts that the people who made these worshipped this otherwordly presence, did rituals of blood
After people went insane because of the tunnels, they blew the enterance to it up.
The final confrontation with the Beast takes place in one of their ritualistic fighting arenas, which had seemingly been very close to a rift to the Other World, which allows The Shadow to appear (basically the overlooming antagonist of all of the Amnesia games), as well as a Harvester Nest (which is surrounded by the fluid that transforms them into Harvesters, the same fluid that turns Augustin into The Beast)
