According to the Population Reference Bureau, there are approximately 101 billion dead people on earth with 7 billion more to join them within the next century. With the dead far outnumbering the living, it’s no surprising that space at cemeteries has become premium.

Many European countries have been reusing graves for centuries. In the Old Jewish Cemetery in Prague, when space runs out, a fresh layer of soil is laid out on top of the existing graves to make room for new bodies. When the last burial took place there in 1787, there were already twelve layers of graves stacked on top of each other.

A cemetery in Hong Kong built on a terraced hill. Photo credit: Michael Chu/Flickr