An hour away from Berlin by train sits an enormous hanger, the biggest free-standing hall in the world. It is located in the middle of a former Soviet airfield, and was initially built as a base for a new generation of airships. These airships were never built.

The dome is now a fun palace called Tropical Islands, a resort in which Berliner families enjoy an indoor rainforest, pools, a sauna complex, and crazy golf. Bars and restaurants litter the complex, which is open 24 hours a day.

It also has an indoor hot air balloon.

With happy but vague memories of visiting Centre Parks’ first UK venture in the remnants of Sherwood Forest some time in the late 1980s, I decided to go along. To get there, you get a train to a station in the middle of nowhere, where a brightly painted bus meets you straight from the airport. You might as well get on. There’s nowhere else to go.

Soon the bus was riding along a runway past brutalist-tellytubby bunkers that might have been holiday chalets, or else just Cold War remnants. Up ahead was the vast fun bunker. It loomed.

Inside, the temperature was in the late twenties. There were two queuing systems, one for day visitors and one for people who would never leave. On arrival you are given a wristband, which explodes when you turn thirty with which payment for drinks, rounds of crazy golf, and other entertainment can be automatically logged.

There were two ‘islands’ within the resort. The first centred around a collection of disappointingly lukewarm swimming lagoons, with vast artificial beaches lined with large numbers of sun loungers. As it was a midweek afternoon in early November, the centre wasn’t particularly busy, but the EU-funded German stereotypes commission will be glad to note every single lounger was baggsied with a towel.

The main lagoon backed onto the edge of the dome, with a huge illustration of a tropical sea hung from the wall. I swam towards it, like Truman in the last episode of his reality TV show, but I didn’t find God. The lagoon had ersatz tropical islands, from which exotic dancers performed occasional shows to a soundtrack of europop to the audience of disinterested German sun loungers.

The second ‘Island’ was the spa resort, which was more the reason for our visit. And what an odd place it was too. The saunas all had strange themes, with one, for example, taking the appearance of an ancient Mayan temple. Surrounding each sauna were more tropical plants, and space for more sun loungers and fake beaches. On one of these, I dozed, occasionally waking to gaze up at the giant roof, unsure now whether we’d been there for minutes, hours, or years.

I closed my eyes, and my ears filled with the sound of inexpert bongo drumming coming from some unknown place. The PA from the lagoon island started up again, and the sound echoed off the faraway roof. I imagined that the resort was an enclave for the super-rich, and that outside was climate change ravaged badlands. Armed guards protected the dome from desperate outsiders, while we chosen few led a life of pointless luxury, of permanent bathing, and drinking cocktails in our bath robes. Forever.

Until then, it’s a nice place to go to watch normal, occasionally naked Berliners relax and have sensible, family friendly, climate-controlled fun.