[amorphous]

Nuclear bunker if sealed up airtight with proper doors.

Their plan for continuation of government perhaps - same as we have elaborate structures for our leaders to evacuate to today at a moments notice.

An event took place approximately 12,000 years which killed millions of humans and animals worldwide like the Clovis people of North America, mastodons and other large mammals worldwide.

Relatively fresh memories/legends may have indeed led to construction of these massive structures for protecting the elite of their day, not only in Egypt but in the Americas as well.

[sparklite2]

Nukes, I tell ya.

Roughly 12,900 years ago, massive global cooling kicked in abruptly, along with the end of the line for some 35 different mammal species, including the mammoth, as well as the so-called Clovis culture of prehistoric North Americans. Various theories have been proposed for the die-off, ranging from abrupt climate change to overhunting once humans were let loose on the wilds of North America. But now nanodiamonds found in the sediments from this time period point to an alternative: a massive explosion or explosions by a fragmentary comet, similar to but even larger than the Tunguska event of 1908 in Siberia.

http://www.scientificamerican.com/article/did-a-comet-hit-earth-12900-years-ago/

[PIF]

Protecting elite or gain storage equally dumb.