This famous riddle asks: What has cities but no houses, forests but no trees, and rivers but no water? The clue sounds impossible until you realize it is describing a representation of the world rather than the world itself.
The answer is: a map.
A map can show cities, forests, and rivers, but none of them are physically present on the page. The cities have no actual houses, the forests have no real trees, and the rivers contain no water. They are symbols and labels used to show where those places are located.
This is one of the most popular classic riddles because every clue fits perfectly once you see the answer. The challenge is simply to stop thinking literally and picture something that can contain all those features without containing the real things.
