A Look Back: Star Wars Celebration V Diorama Workshop: Hoth
For sheer size, the Celebration V Diorama Workshop build of the battle of Hoth may be the largest diorama to this point. The sprawling layout included the battle between the Rebels and the approaching AT-ATs as well as a large hanger full of X-Wings and Snowspeeders, plus countless rooms full of Rebels and Imperials fighting or going about their day in spite of the battle.
The diorama was so big, it was actually hard to photograph so a lot of the detail of the Rebel base is included in the video below. The photos try to give you an idea of how large the battle part of the display was, while highlighting a few funny pieces of the build.