Cities depend on systems that already exist around them. When architects design on water or beyond Earth, those systems are no longer available. Without fixed ground or nearby networks for energy, water, transport, and waste, architecture has to take on functions the larger city would normally provide.
The reason for moving beyond familiar ground also changes from one project to another. In the Maldives, building on water responds to the vulnerability of existing land. In Busan, floating development creates another direction for urban expansion. On the Moon, the challenge is more absolute: there is no existing infrastructure to connect to at all.
