As Finland mulls its possible entry into NATO, residents can feel a sense of safety thanks to the decades-old network of more than 54,000 bomb shelters mandated by the country’s Rescue Act, which requires any currently in-use buildings with a floor area of at least 1,200 square meters (12,900 square feet) to include such facilities. 

A total of 85% of the shelters are operated privately, with most serving more practical peacetime roles as sports centers, shopping malls, and in some cases parking garages. The country’s past preparedness for other emergency situations paid considerable dividends at the outset of the pandemic, but Finnish civil defense officials maintain they aren’t looking forward to a system-wide litmus from the Russian military anytime soon.

“It’s sad to see what is happening in Ukraine,” Tomi Rask, a safety instructor at the civil defense center in Helsinki, told the Guardian. “I see the poor people hiding in the metro or in theatres. It shows again how important it is what we do. I don’t want to brag, but the Finnish bomb shelter technology is one of the best. We have been doing this for a while.”

Finland began constructing the shelter system at the height of the Cold War; in the end, producing slightly less than the 65,000 shelters neighboring Sweden has. Notable structures like the Amos Rex Art Museum and Suomalainen brothers’ Temppeliaukio Church have become Instagram-friendly subterranean attractions, and the nearly 200-mile network underneath the capital has given Helsinki an added neighborhood useful to its 600,000-plus residents in times less dire need.

“It’s comfortable and safe,” Helsinki’s chief underground planner Eija Kivilaakso said in an interview with Atlas Obscura last year. “If it’s raining, you can drive into the city center to an underground car park and go straight into department stores from elevators. You can dress for comfort instead of in cold-weather clothes. If the weather is not comfortable, people choose the underground.”