#industrial plumbing to the right, down the center is passage way, and hey while you have the space show school students art work. This is one of the tunnels that connect the House to Senate mitigating the need to walk outside in Washington, D.C.. If anyone has ever wondered “why don’t we see politicians walking outside” this is why. And in the summer months I refer to it as the suite-saver as it gets uncomfortable in the sun when one has to go outside to get access to another building; occasionally the tunnel(s) is closed due to various reasons. And yes there are multiple below ground interconnecting tunnels.