Why are there giant concrete tunnels in the desert?

Seems like they gave her a tour with a little extra completely inaccurate hype, as that AC unit is a "outdoor" unit never installed inside a building and the isolation springs are standard seismic isolation to keep from cracking the concrete not to protect LIGO from detecting movement.  I guarantee they either turn this unit off when doing any actual testing, compensate for vibrations  or their testing is completely inaccurate.