It may sound crazy but it almost looks like little apartments/ housing. When I was there last night I though wouldn't it be awesome if they opened it up and we got our own room/ housing apartment, they would have in there some EXTRA vault storage room and trophies or even a area to read our Grimoire Cards. It wouldn't be that hard to do as the tower only holds a certain amount of people at a time, they could give the same rooms to everyone at the tower at that certain time, then just refresh for the next bunch of guardians.