Nakagin Capsule Tower
The building is actually two towers. One is eleven and the other is thirteen floors. These towers are the utility cores. They have the elevators, stairs, electric, and water services in them. They also support the whole building. 140 capsules are attached to the two cores. Each capsule unit is one apartment or office. They are  ×  ×  and have one round window. Just four bolts connect each unit to a tower. The units are made from lightweight steel. They were built in Shiga Prefecture and brought to Tokyo on trucks. The capsules are not connected to each other, so any capsule can be removed or replaced without moving the others.