The Longyou Caves were only discovered late in the 20th century. At least 24 caves have been discovered so far. All of which were carved by hand. Although the overall excavation involved almost a million cubic metres of stone, there is no historical record of them or evidence of the work. Their origin is a complete mystery. At present there is no explanation for their existence. They represent one of the largest underground excavations of ancient times.
In the aftermath of a natural disaster, the challenge of quickly and sufficiently providing aid and shelter to victims has been highlighted in major events like Haiti's 2010 earthquake and Japanese tsunami and nuclear disaster of