These weren't nice, friendly Blast from the Past-type vaults, either. One was a gaping void bigger than an Olympic-size swimming pool. Another was full of so much water, they had to haul in 600 tons of rock to drain it. They even found freaking munitions in one of the chambers, no doubt leading to unprecedented levels of safe feelings in the heavy-equipment operators charged with finding the chambers.
Nobody knows why these bomb shelters were built or why so many were thought necessary. When the construction company checked, it turned out the food-processing plant built over them was old enough that they just didn't have to keep records on that kind of thing. We can only hope they stop digging before they hit a secret cache of Brendan Frasers.
"Release us ..."