I'm always a huge fan of dark photography as long as you can still make out the details of the main subject(s). So that being said, I love the exposures you've gotten.
Two biggest things that jump out to me:
- Pay close attention to centering your composition. I can see what you're trying to do with the hallways shots especially, and you got REALLY close to perfect centering...but they feel very very slightly unbalanced still due to the photos not being taken from the exact center of the halls (look at how the ceiling's lines are slightly off from center). The second shot got it almost right, but it feels a little off kilter since the lines in the door at the far end of the hall aren't straight up and down.
- It seems like the second shot was taken from a standing position, and because of that there is a very slight downward lilt to its framing. Hallway shots are always more effective from the perspective of the first shot; you got the vertical positioning of the camera exactly right for that one.
I would say the third and final shot is not as strong as the other two because of the vantage point the picture was taken from and the off-balance crop of the photo. Places with lots of lines like that auditorium has look much better when you either follow them very closely with your framing, or deliberately go against them. This shot feels more like a quick candid exposure on the go, whereas the other two feel far better composed. I personally would not include it in a set, but if you feel strongly about it, I'd bring up the brightness on this one just a tad, and perhaps brighten up the person on the left of the frame just a little bit to draw the eye to him.
Excellent locations and good work! Keep it up.