The Clown Town can be upgraded by Clown Town Upgrade Kit item. To upgrade the Clown Town, use the Clown Town Upgrade item on the Clown Town that is already situated in your city. Its upgraded version will then be placed directly on the same spot in your city and the production timer will not be reset. Note that the upgraded building will be from your current era, even if the old one was from one of the earlier ages.
Clown Town will produce the following effects. Base effects will always be produced. Bonus effects are determined by how many other unique Horror Circus Set buildings it is connected to.