Remember that giant temple entrance? Yeah:
Basically, this is a part-intro-part-final dungeon. The first visit is a simple climb up; the side doors present on most floors are locked and the blocks in the middle are deactivated so you can climb up fast and without having to do anything tedious. The second (and final) visit is when the dungeon begins to turn into a final dungeon; the blocks are activated and the doors on the sides open forcing you to go through a series of trials on each floor.