What is the collective noun for cities?

There isn't a single, widely accepted collective noun for cities. However, here are some options you could use, depending on the context:

Formal:

* Conurbation: This term refers to a group of cities that have grown together to form a single, continuous urban area.

* Metropolis: While this usually refers to a large city, it can also be used to refer to a group of significant cities.

* Urban agglomeration: A technical term used to describe a concentrated urban area.

Informal:

* Collection: This is a general term that can be used for any group of things.

* Cluster: This suggests a group of cities that are close together.

* Network: This term emphasizes the connections between cities.

Ultimately, the best collective noun to use will depend on the specific context and the effect you want to achieve.