Ecumenopolis

An ecumenopolis is a world city or planet-wide city. As a type 0 civilization progresses towards 1, urban areas and megalopolises would eventually fuse and there could be a single continuous worldwide city as a progression from urbanization, population growth, transport and human networks.

A planet spanning city is only sustainable if there is a sufficient and steady import of food and resources from nearby planets or star systems. This is more plausible for a Type-1 civilization.

When planetary cities grow in an unsystematic and unplanned manner beyond normal boundaries, due to increases in population and industry, so that their suburbs merge into the suburbs of neighboring cities, the result is a vast extended metropolis called a sprawl. These megacities can merge and sprawl across a planet. If it goes beyond the planet it is called a swarm where there could be thousands or millions of habitats surrounding a star.

An example of an ecumenopolis is Coruscant.