These architects were interested in building housing for large numbers of people. They often planned buildings that could be changed. One example is the Nakagin Capsule Tower by Kurokawa (1972). Each apartment was a rectangular block with one round window. These blocks could be added, moved, or removed as needed. It was a ""plug-in building"". Kurokawa planned for new, better capsules to be added to replace old ones. However, people living in the tower plan to tear it down and rebuild a larger building. 