Cauldron XI is a HEPHAESTUS facility that manufactures machines for use in terraforming.
Unlike the other Cauldrons, XI appears to have been rendered unusable due to a natural cave-in. Eclipse cultists have discovered the area and built extensive structures and fortifications in and around the dig site. The central core is still active, and can be overridden. Much of the facility still has power, and what appears to be a recycling center that melts down machine scraps is still functioning.
In order to progress through this Cauldron, the player will have to first do battle with cultists and corrupted machines to progress deeper. Once Aloy overrides the Cauldron, normal machines will be alerted and will breach the encampment to attack both the Eclipse and Aloy. The player will have to fight both the cultists, and Watchers, Ravagers, and Stalkers in order to escape.