Many (many) years ago I worked for the Earth & Space Sciences department at the University of Washington (setting up some of the first GPU farms! If only I'd known) and the lab where Minze Stuiver calibrated the Carbon-14 (and O18 and St90) timelines was in the sub-sub-sub-basement -- a single room with a descending spiral staircase in a storage room next to where they kept the ice cores. The facility was a kiln built from lead bricks made from the keel of a boat sunk before the modern atomic era.

A photo of the apparatus with the lead to the right: https://www.flickr.com/photos/jedwards/2281494063/

and a close-up of the kiln: https://www.flickr.com/photos/jedwards/2282285754/

IIRC a year or two after I left, they filled the whole space with concrete to build the foundation for a new neighboring building. They found someone who wanted the lead and bucket-brigaded them out of there, which must have been quite a day (the bricks are about 25lb each, and the size of a normal brick)