Researchers from Brigham Young University, in Utah, are trying to find why a million mummies are buried near Pharaoh Snefru 's Seila pyramid.
About 4,600 years ago, Snefru initiated one of the greatest construction projects in human history.
For reasons yet unknown, he decided to build four pyramids scattered at different places across Egypt.
Two were constructed at Dashur (the Red and Bent pyramids), one at Meidum and another at a place called Seila.
Together they used up more material than Khufu's pyramid at Giza.
Using casing stones they were given a smooth appearance - in other words make them into "true pyramids." This was the first time in Egyptian history that this was done.
And now the BYU team is investigating why Snefru built four of the pyramids in the way he did.
One of the puzzles the team is trying to decipher involves a cemetery not far from the Seila Pyramid.
It's a 40-minute hike away and research indicates that it has an enormous number of mummies.
"We estimate over a million bodies in this cemetery," Prof Kerry Muhlestein told The Heritage Key.
It's "very very densely populated by mummies," he said.
Only a small percentage of them have been unearthed.
Muhlestein said: "We've been digging there for 30 years and we could dig there for a hundred more and still have only done a small percentage."
Results suggest the cemetery was not in use during Snefru's time.
In fact the earliest burials appear to be from the Middle Kingdom - at least 600 years after the Seila pyramid was constructed.
Moreover, most of the burials are even later than that.
Muhlestein said: "For the most part the cemetery is Graeco-Roman period, from the Ptolemaic era down to the end of the Byzantine era."
This period started when Alexander the Great entered Egypt in 332 BC.
So the question is why did so many people - who lived long after Snefru's reign - choose to be buried so close to the Seila Pyramid?
The mystery becomes more interesting since this wasn't just a local cemetery. People seem to have come some distance to be interned here.
Muhlestein said: "It's such a huge cemetery it's hard to account for where all these people would have lived - the population centres around there don't seem to substantiate that many burials.
"Maybe these are people coming from a variety of communities, all around, being buried in this place. We're not sure what would account for such a large number of burials."
Muhlestein believes there be a connection to the pyramid.
He said: "It probably is at least partially responsible for why there's a cemetery there," said Muhlestein.
"It seems very reasonable to suppose that the pyramid designated that as a sacred place.
"Once that place is a sacred place it typically will remain a sacred place." (ANI)