The Serapeum is New Kingdom in date, rather than middle kdm. It would still be remarkable if the big boxes had been installed via the pit and sand method used for various tombs -- a pit was excavated, filled with sand, then the sarcophagus pushed out onto the sand, and the sand removed by hand (labor, ropes, ladders) allowing the sarco to settle to the bottom. At that point the sarcophagus was moved into the burial chamber, awaiting the guy or girl to die. If the Serapeum boxes had been dropped in from above in that manner, and then the chambers built over them, it would still be impressive, but it's much more impressive this way.
What Graham Hancock Really Thinks About the Advanced Civilizations of Prehistory | ZEG TV Hidden from the Public | Published on October 5, 2018
Graham Hancock goes around the world explaining his theory of a lost civilization. Looking at Baalbeck's huge stone blocks, Egypt's Giza Pyramids Turkey's Goblekli Tepe, Japans Yonaguni underwater structures and a whole host of other historical sites. After viewing and researching these sites along with other geological evidence he has come to the conclusion the a comet struck Earth 12000 years ago and caused a global reset of an advanced civilization. Was this civilization the famous Atlanteans?