The biggest uninterrupted indoor space on the planet, Tropical Islands Resort ( https://www.tropical-islands.de/ ), sits on an old airfield in Germany. How on earth could anyone afford to build something that big... and then use it as a waterpark? Well, the story's a bit more complicated than that.
(And full disclosure: this isn't a sponsored video, no money's changed hands, but Tropical Islands were happy to let me in free and give me a ride up on their balloon. I'm grateful to all the team there for a fantastic day!)
