City of Endermania, built in survival mode over a Stronghold location. It is populated by villagers from generated villagers that were brought to the location. Temple and monuments were added as in game goals were reached. Unfortunately the city became a victim of it's own success as its 300+ villager population became outnumbered by Golums, and no amount of raids (120 waves!) could reduce the golum count to something reasonable. But it was great fun while it lasted.
Good idea. My original idea was that the golems would go through the End portal under the city, but never got around to excavating an descent path big enough. In the end it was fun just to watch so many golems thrash waves of raiders . Never did get around to opening the End Portal :/