Answer: The Capitol Building

The United States Capitol Building is a massive and iconic piece of American architectural history. The main building and surrounding outbuildings and structures are built almost entirely of marble and granite quarried in nearby Virginia.

It is the enormous volume of marble and granite found on the premises that give the Capitol Building a dubious and unseen claim to fame, as both stone types are naturally radioactive thanks to trace amounts of uranium. The radiation levels in the building are 55 times higher than the permissible levels of radiation exposure allowed by the EPA at the outer-most perimeters of nuclear power plants. Essentially, if the Capitol building were a nuclear facility, it would fail a safety examination.

Now, before you incorporate a lead vest into your next trip to the the Capitol, rest assured the EPA guidelines for containment and exposure levels at nuclear plants are purposefully extremely low (which should reassure you of the safety of nuclear facilities) and that the levels of radiation in the Capitol Building, while high compared to non-granite/marble buildings, are still well within safe limits for visitors and staff.