A long time ago, in a village far, far away, some disturbed townsfolk decided to destroy their entire town in order to rid themselves of an evil menace (it's technically a dog-mouse, but I think it's an idiomatic thing). Anyway, so the villagers rebuilt all the buildings in the town (including their precious outhouses), but forgot to include city walls, a river, or roads. To rectify this, players lay tiles with one of these three things onto the board, and any building caught underneath them is automatically eliminated, except for outhouses. When an outhouse would be destroyed, players take a vote on whether to place that particular section. Each player is trying to retain the most of one type of building, and once all the pieces have been placed the winner is the person with the highest valued buildings still standing.
