Smithsonian.com

In the middle of the 14th century, the black plague hit London, killing in a year and a half as many as 40,000 people. “There were so many dead that Londoners had to dig mass graves,” says the Museum of London.

In some of the trenches, the bodies were piled on top of each other, up to five deep. Children’s bodies were placed in the small spaces between adults. By 1350 the Black Death had killed millions of people, possibly half the population of the known world.

During recent construction efforts in London, archaeologists announced the discovery of a pit, 18 feet wide, housing the skeletons of people thought to have been killed during the earliest waves of the the black plague’s rampage across the Europe. NPR:

Thirteen skeletons were found lying in two neat rows about eight feet beneath the road in central London, as workers surveyed land for the Crossrail project, a transportation effort that’s building new rail lines for London. It’s believed they’re from a bubonic plague outbreak in 1348: researchers also found pottery dating from that time period, and say the depth at which the bodies were buried, also indicates an approximate time of death.

The relative organization of the bodies in the pit, says The Independent, suggests that these Londoners were killed before the chaos of the full-blown black plague outbreak.

Experts believe that the skeletons’ arrangement in two neat rows suggests they date from the earlier period of the plague, before it became a pandemic and before bodies were thrown randomly into mass graves.

In the land around the excavation site, says NPR, “as many as 50,000 people could be buried in the area. Records suggest these no man’s land burial grounds for plague victims were used through the 1400′s, but no evidence of a huge cemetery has ever been found.”

The Independent: “Although that number is now widely believed to have been an exaggeration, the discovery of further remains has not been ruled out.”

According to The Independent, any fears that may have sprung to mind about disturbing the peaceful slumber of these medieval skeletons, is—fortunately—misguided:

Mr Elsden was quick to reassure the public that there was no longer any health risk from the plague which killed over a quarter of the British population in 1348.

“It’s not something that stays in the soil. You have to actually meet someone who has it in order to catch it.”

That being said, recent research suggests that the black plague is still a threat today—maybe even more-so than before. Though better preventative measures and quarantines and health surveillance programs exist now than they did in the middle ages, the emergence of antibiotic resistant strains of the bacteria that cause the plague is a worrying development.

More from Smithsonian.com:

The Black Death Never Left – And It Might Defeat Our Best Defenses