Today, more than half of humanity lives in cities.
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.
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.
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.
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