This data-pack adds a randomly generated dungeon, that ranges in size from very small to absolutely massive. With many staircases, corridors, secret rooms, and multiple levels expanding out 100's of blocks.
one of the randomly generated corridors
This is an older photo - rooms are updated a bit but the dungeon itself is unchanged from the pic. And L turns, those are in the current version too.
Dungeon main hall
a library with some loot chests
Room with loot chests and some ores, upper level
one of numerous hidden rooms in the dungeon
Corridor of the lower level - better loot, stronger enemies