We went to a local fun fair and they had a themed tunnel extravaganza made entirely out of cardboard! They took an entire gymnasium and turned it into a themed city. It was so big that they had knee pads for you to wear because all of the crawling. It had 6 different rooms that were big enough to stand in. In the rooms, there were actors who tried to convince you which route to take to continue through the maze. There were cardboard steps to higher levels and cardboard slides to lower levels. There were even secret passageways that could only be found by following the posted clues. For your comfort while making your way through, there were towers with fans at the top to circulate the air through the maze. You exited through a slide that brought you out of a lion's mouth by sliding down it's unfolding tongue.
It was literally amazing!