Sources for this episode:

* Wikipedia: Great Pyramid of Giza (https://en.wikipedia.org/wiki/Great_Pyramid_of_Giza)

* History: The Great Pyramid took about 20 years to build (http://www.history.com/news/ask-history/how-long-did-it-take-to-build-the-great-pyramid)

* The labor force was primarily skilled workers

* Harvard Magazine: Who built the pyramids? (https://www.harvardmagazine.com/2003/07/who-built-the-pyramids-html)

* PBS NOVA: Who built the pyramids? (http://www.pbs.org/wgbh/nova/ancient/who-built-the-pyramids.html)

* The Guardian: Great pyramid tombs unearth 'proof' workers were not slaves (https://www.theguardian.com/world/2010/jan/11/great-pyramid-tombs-slaves-egypt)

* What did these people eat?

* Live Science: Giza secret revealed: How 10,000 pyramid builders got fed (https://www.livescience.com/28961-ancient-giza-pyramid-builders-camp-unearthed.html)

* Smithsonian Magazine: The beer archaeologist (https://www.smithsonianmag.com/history/the-beer-archaeologist-17016372/?no-ist=&page=2)

* National Geographic: The pyramid builders (http://ngm.nationalgeographic.com/ngm/data/2001/11/01/html/ft_20011101.5.fulltext.html)

* The Earth Pyramid (http://www.earthpyramid.org)

* Nature: Discovery of a big void in Khufu's pyramid by observation of cosmic-ray muons (https://www.nature.com/articles/nature24647)

* How did they actually build the pyramids?

* Newsweek: Who built ancient Egypt's Great Pyramid? Hidden text holds clues to thousand-year-old mystery (http://www.newsweek.com/who-built-ancient-egypts-great-pyramid-hidden-text-holds-clues-thousand-year-670265)

* How secure were the tombs?

* PBS NOVA: Missing tombs of the pharaohs (http://www.pbs.org/wgbh/nova/ancient/missing-tombs-pharaohs.html)