The third photo is a lovely scene and makes me wish I could be there. As to your son's head ... yes, it is distracting in this frame, and a bit of play with the clone tool might do the overall photo some good. You were wise to wait for people to be around for this fact gives the photo much more life (literally, and figuratively).
Composition of the second is too straightforward, too central, too ... boring. The building is certainly interesting, old as it is. Little chance for you to return and re-shoot (immediately NOW, that is), so you might try to crop your photo so you move the building a bit out of the dead centre of your image.
In the first, the dynamics are too wide for the camera to capture, too dark inside the tunnel, too bright at the end. Though some post processing, first masking one part, later the other, might work (but only to a certain extent).