Nearly 200 miles of tunnels snake beneath Helsinki, providing a weatherproof subterranean playground for the Finnish capital’s residents and visitors. Yet hidden behind the bright lights of the underground attractions—which include a museum, church, go-kart track, hockey rink, and more—are emergency shelters fitted with life-sustaining equipment: an air filtration system, an estimated two-week supply of food and water, and cots and other comforts. The shelters reflect a chilling geopolitical reality for a small country that shares an 833-mile border with Russia, its longtime nemesis. Thought to be the world’s only…
