Under the Finnish capital lies a world of swimming pools, go-karting tracks, playgrounds – and even an art gallery The moon is an impostor. Swimming backstroke beneath its surface, I look up at craggy hollows in close relief. White rock undulates in all directions, a forest of peaks rising next...
Source: [Guardian International](https://www.theguardian.com/travel/2026/sep/24/helsinki-finland-underground-city-swimming-pool)