Treetop cities are a type of fictional city or town suspended high in the canopy of a forest or jungle or fixed around the upper trunks of giant trees. These places may be built around and throughout the vegetation or be grown from it. They may have elaborate bridge networks connecting the various locations, buildings, and tree houses. They may be found in forests of giant trees. Treetop cities are home to elves and arboreal species.

When designing treetop cities first consider why a people would build their city high in the air in the first place. Perhaps there is danger below or resources in the upper levels of the trees. Also consider how people and things are transported to these upper levels from the ground