The idea of the tower was first presented in "A Seat at the Table" when the Joker pitched the idea of building a giant tower with his face on it where his "mouth" would open up to reveal a giant TV with him on it during the Legion of Doom's weekly pitch-meeting. He said he would need 800 million dollar to build it but would settle for 600 million. Everyone at the meeting were all in until Harley Quinn started questioning why he needed to build a tower to begin with, making them all see that his idea was a bit half-baked.
In "Devil's Snare" the Joker had put his plans to reality when he blew up the Hall of Doom and then had his tower rise from the ground (an idea he had gotten from Harley). He used his giant TV screen to announce that the Legion of Doom used to stand for something but he now looked down on it for letting in the liked of Harley Quinn which is why he destroyed it. With his tower in place, Joker took over Gotham.
In "The Final Joke" Batman teamed up with Harley and her crew to take him down but he managed to capture them all (except Harley) and held them captive in the tower for weeks. Harley finally surrenedered herself in exchange for him letting her crew go which he did and he took her to a special room, resembling Ace Chemical Processing Plant to drop her in a vat of acid which would turn her "normal". However, she was saved by Poison Ivy who then dropped Joker into the acid. Before he was turned normal, he managed to reach up and press a button on his watch to destroyed the tower. The destruction of his tower resulted in Batman being buried and later found in a coma and caused a 8.6 earthquake which destroyed much of Gotham and threw the city into chaos.