This article about a location is a stub. You can help the One Piece Wiki byexpanding it. Please be aware that when you are watching official English translations that there may be name variations that are different from what is used on the wiki. Please read here for further clarification on what to use when writing summaries.
Devil's Tower is Ganzack's tower which was created in Medaka's home town. It was later revealed to be a hidden cannon designed to destroy the rest of the island.
Herring and all the other male villagers were forced to work on constructing the Devil's Tower, without knowing what it was being made for. Later, during Luffy's battle with Ganzack, it was revealed that Devil's Tower was nothing else than a cannon made with the purpose of destroying the whole island except for Ganzack's pirate ship.