Question

What has cities, but no houses; forests, but no trees; and water, but no fish?

Answer 1

Hey there!
Love this riddle :)
Your answer would be a map. Maps show all these things quite two-dimensionally and map them out for you, but they don't really have these things physically. They're often just pictures.
Hope this helps!

Answer 2

A map.  you can look on a map to see what cities but it doesnt show the smaller details.