Over the last few decades architects and designers have been busy burrowing. Rammed earth structures, reclaimed war bunkers, and homes dug into hills have turned buildings inward instead of upward. Here we present a gallery featuring the most fascinating, weird, and experimental underground designs from recent years.

As well as offering the energy-saving benefits of the surrounding earth acting as insulation, many of these compelling structures seem to disappear into their environments. From the grass-covered pyramids of the Biesbosch Museum Island to the Great Wall of WA in Australia, many of these buildings sit in perfect harmony with their surroundings.

On the other hand some are truly mind-boggling designs that completely stand apart from their environment, whether it's the upside-down Earthscraper, an underground skyscraper proposed for Mexico City, or the gorgeously minimal House In Leiria, a windowless house that disguises a large underground residence.

Take a look through the gallery for a trip through the best of underground architecture.

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