These are some of the coolest underground buildings in the world

Today, more than half of humanity lives in cities.

And we’re only getting more urban — by 2050, at least two-thirds of the world’s population will call cities its home.

Yet you can add only so many skyscrapers to squeeze in the flocking masses.

Building underground, however, is an option.

According to a 2013 report by the US National Research Council,
exploring underground “may be the most successful way to encourage or support the redirection of urban development into sustainable pattern.”

While experts figure out whether digging into the ground can solve the urban space problem, we take you to some of the world’s most unique underground marvels.

Built in 2009 in the memory of a Korean poet, the Earth House in Seoul has two courtyards connecting six single rooms, a kitchen, a study, and a bathroom with a wooden tub and toilet.

Yongkwan Kim

Built into a rock, the Temppeliaukio Church in Helsinki gets ample sunlight through a glazed dome. Those rough rock walls were left untouched by the designers for a reason: naturally great acoustics make the church a perfect venue for concerts.

Jorge Láscar/Emporis

Built in 1996, this hobbit-like house in the Welsh countryside is a tunnel under a turf roof. The three-bedroom house with stunning ocean views resembles a home that featured in a famous British children's TV show -- locals call it the Teletubby house.

© Simon Mortimer and licensed for reuse

This subterranean bedroom in the Australian mining town of Coober Pedy is ideal for a desert where temperatures can climb to 122 degrees Fahrenheit in the day and fall to 30 at night. Half of the 3,500 residents have dug their homes into clay rocks.

Torsten Blackwood / Getty

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