I had a few nano tanks in my dorm when I was at college but we werent allowed any fish or inverts (plants only) and idiots kept pouring drinks or ferts into the tank when I wasnt looking so most of them were just a mess of algae. I did however have a sneaky one in my cupboard for a while! Liberated a baby pike from an idiot sport fisheries student who had tried to keep 2 in a tiny filterless goldfish tank in his room, one jumped out and I had the rest, he lived in there pretty happily for a few months until I tried to take it home to a larger tank/pond and unfortunately died in transit.
My tanks are in my bedroom at home, cant have them anywhere else in the house as the rest of my familly would kill me. I think the most i had in here at one point was 9 tanks: 160L, 60L, 30L and a few others mostly nano/breeding tanks. I was always having to re-arrange my room to fit them in! I even got rid of my bed and slept on the floor for 18 months so I could fit my 100cm marine/octopus tank in here. However Since those younger days though I have always had a maximum of 2 aquariums in here as I have a nice double bed and wardrobe now! Although that said, since I got the larger bed and wardrobe I somehow managed to fit my largest aquarium yet in here and still have more floor space than iv ever had before! Anways a few pictures of how it is currently configured!
Nano at the top of the stairs leading into my room, currently in the process of re-building the cabinet so I can stick all the equipment out of sight but currently days off and free time are few inbetween work and fishing. The door leads into my bathroom which is actually treated more as a store room for equipment, substrate, buckets and barrels.
Amazon biotope aquarium at the end of my bed, got a bit of work in progress with this tank at the moment raising the shelves, adding more light and turning it into a paladarium, also adding some extra legs to the stand and a front to cover the sump now I have decided to stick a trickle filter in and and that I am not going to scape it or keep anything in it.
P.s. My room isnt always THAT messy, sometimes its worse!