Enter "/Location Fortress" in the command box, and it will display "The nearest hell fortress is located in X, Y and Z". These three numbers are the location of a hell fortress.
The lower bound fortress is a naturally generated structure in the lower bound, which consists of many bridges, corridors and towers. The lower bound fortress can be generated in any lower bound biota. When the lower bound fortress is generated, the game will divide the lower bound into several areas in a certain way, and only one lower bound fortress or fortress relic will be generated in each area. The size of each area is 432×432 or 480×480.