There’s a tunnel leading into the capital that I know for sure exist. It’s actually still in use, which is why I was down there. It’s used to secretly, and securely get senators into the building, and into their offices. I was there a few years back with a certain senator for a special event, and this is how we entered. I’m sure they probably also use more open means(in public view) of entering, but these tunnels do exist and are used.

I’m not sure how far they extend away from the capital, or if they do at all. It would make sense to me that they do though. These looked like normal corridors for the most part, but weren’t decorated or anything.