A really immense room spells big complications. Just the kind of thing D&D players gear up for.
A really large dungeon floor tile stands right at the middle of the encounter. It gives you room to lay out epic battles. You can fill it with puzzle after puzzle. Since it is part of a modular dungeon, you can easily pack it up at the end of play.
Combine this dungeon floor tile with other tiles to create underground tombs, crypts, and temples. Adding a few pieces of 2.5D furniture and fixtures creates a rich easily played room that keeps everyone on their toes.