Michael fortress is the base of operations for the archangel Michael of Apocalypse World on Earth. The fortress is a dilapidated church, located somewhere in the vicinity of Kansas or Nebraska in the Great Barren Plains (formerly known as the Midwest). It has warding so powerful that it can dampen the powers of a Nephilim and cause headaches to a regular human.
After being captured by Michael, Lucifer was placed in a spiked hanging cage in Michael's fortress, where Michael proceeded torture and tap into Lucifer's mind to learn more about Lucifer's home universe.
When Kevin Tran figures out a method to open a rift, Lucifer is brought to the chancel area of the church, where Michael extracts most of his grace to use in the spell to open a rift between the universes. In the blow back of the spell being activated, Lucifer was able to free himself from his guards and jump head first through the rift, closing it behind him, angering Michael and demanding Kevin "fix" it.
When dreamwalker Derek Swan uses his powers to help Jack Kline, he sees Mary Winchester suspended in a spiked cage in Michael's Fortress. However, Derek proves to be too weak to hold the connection long enough for Jack to open the portal and rescue Mary. Jack later shares this vision with Sam and Dean as proof that their mother is still alive.
After getting transported to Apocalypse World, Jack finds himself in the fortress at Mary's feet.
Jack Kline is held in the fortress by Michael and Zachariah who try to trick Jack into opening a portal to the Winchesters' world. After Jack sees through it, he is thrown into a cell with Mary Winchester. Together the two realize that the single place in their cell where the warding is weakest is by the window. Jack manages to melt the bars on the window and he and Mary escape the fortress to Michael's fury.
Jack and Mary's resistance receives word that the fortress has been abandoned. Using astral projection, Jack checks it out and discovers that it is true. Jack leads a group of hunters into the abandoned fortress where they find Michael's plans for his armies and Kevin Tran in the dungeon who claims that he has perfected the spell to open the portal and Michael has gone to lead his armies to the Winchesters' world. Mary becomes suspicious at the ease of events and after Jack tries to take off to kill Michael, Kevin reveals it to be a trap. Kevin commits a magical suicide bombing, killing himself and several hunters, though Jack is able to shield Mary from danger. In the aftermath, Jack is devastated by the carnage and his inability to protect his friends.
- Michael's fortress was originally scripted to be a concrete bunker in the desert. When production designer Jerry Wanek was given free reign to build the set, he opted for a dilapidated church look for the fortress.