Medieval residents of the nation's capital may have been just as cosmopolitan as they are today, according to analysis of victims of the Black Death.
An investigation into skeletons found in a plague burial ground concluded that four in 10 Londoners killed during the epidemic grew up in other parts of Britain.
Workers on the Crossrail project unearthed the remains of 25 people in the City of London last year.
The skeletons of 13 men, three women and two children, as well as seven other unidentifiable remains, were found under Charterhouse Square in Farringdon during excavation work for the £14.8 billion project.
Experts said the discovery of the skeletons was "significant", saying that thousands more bodies could have been laid to rest in a mass grave in the area - which at the time was outside of the city boundaries.
They said the finding has provided the first evidence of the location of the second emergency burial ground set up in the capital to cater for the masses of bodies. The burial ground had been referenced in historical documents but until now it had never been found.
Carbon dating techniques conducted by experts at Queen's University Belfast indicated three separate "phases" of burials - coinciding with outbreaks of the plague in the capital during the 14th and 15th centuries.
The Black Death spread from Europe to England in 1348 and the layer of bodies found at the bottom of the excavation site are estimated to have been buried between 1348 and 1349, the researchers said.
A second layer of skeletons have been dated to coincide with a second event of the plague in London in 1361 and the final layer of corpses were buried between 1433 and 1435 - when another devastating outbreak swept the capital.
DNA analysis revealed that four of the people had remnants of the Yersinia pestis bacteria on their teeth - which causes the bubonic plague.
Experts said that all of the signs point to the site being used as a Black Death burial ground.
Many of the bodies showed signs of poor health, the experts said.
They also showed signs of having jobs that involved heavy manual labour as experts noted a high rate of back damage and strain.
The remains also revealed that one of the bodies could have been that of a monk - after showing signs of vegetarianism in later life, which is something a Carthusian monk would have done during the 14th century.
Others showed signs of malnutrition and childhood diseases such as rickets.
One of the skeletons showed evidence of malnutrition and a large variation of diet 30 years prior to death, coinciding with the Great Famine of 1315 to 1317, the experts said.
Six out of 10 bodies analysed were born and bred in London.
But four had come from further afield - presumably seeking work - from the South East of England, central England or the East of England and one from northern England or Scotland.
Osteologist Don Walker, from the Museum of London Archaeology (Mola), said he was "amazed" how much information could be gleaned about each person.
" The skeletons discovered at Crossrail's Farringdon site provide a rare opportunity for us to study the medieval population of London that experienced the Black Death," he said.
"We can start to answer questions like: where did they come from and what were their lives like? What's more, it allows for detailed analysis of the pathogen, helping to characterise the history and evolution of this devastating pandemic."
Mr Walker added: "I was amazed at how much information you can get if you combine the archaeological evidence, the osteological evidence and microbiological evidence.
"There was one individual we looked at and we know that they came to London from elsewhere, we know they were breastfed as a child, we know what sort of diseases they had, we know they had bad tooth decay throughout their childhood, we know they were involved with quite hard work from lesions of the spine, they had a quite active laborious life. The testing also shows that they then died in early adulthood and had been exposed to Yersinia pestis so they might have died from the plague during the first outbreak of the Black Death."
Jay Carver, Crossrail's lead archaeologist, said: " This is probably the first time in modern archaeological investigation that we have finally found evidence for a burial ground in this area which potentially contains thousands of victims from the Black Death and potentially later plague events as well.
"Historical documents suggest the burial ground was established for poor strangers. There is no doubt from the osteological work that the individuals buried here were not the wealthy classes, and they are representing the typical Londoner."
He added: "Analysis of the Crossrail find has revealed an extraordinary amount of information allowing us to solve a 660-year mystery. This discovery is a hugely important step forward in documenting and understanding Europe's most devastating pandemic."
Forensic geophysics techniques have shown that there are potentially more burials across Charterhouse Square.
In July this year a "community excavation project" will take place to try to determine the extent of the cemetery.
A similar skeleton formation was found in a Black Death burial site in nearby east Smithfield in the 1980s. Experts are now planning to compare the data gathered from the two burial sites.
Meanwhile, scientists are also working on sequencing the genomes of the skeletons.
Around 1.5 million Britons died in the Black Death - more than a third of the population - while about 25 million perished in Europe.
Since the Crossrail project began more than 10,000 items of archaeological interest have been uncovered, a spokeswoman for the project said.
These are not the first skeletons found during the project, with archaeologists already uncovering more than 300 at a known burial ground at Liverpool Street in London that dates from the 1500s to 1700s. That burial ground was located near the Bedlam Hospital.
Experts have also found 30 skulls from the Roman period near the same station in one of London's lost subterranean rivers, the River Walbrook.
A prehistoric "flint factory" from the Mesolithic period was also found in North Greenwich.
Crossrail is Europe's largest infrastructure project. Stretching from Maidenhead and Heathrow in the west, across to Shenfield and Abbey Wood in the east, the railway will cover more than 60 miles of track including 13 miles of new twin-bore rail tunnels and nine new stations.
:: The findings will be featured in a new Channel 4 programme, Return Of The Black Death, which will be aired at 8pm on April 6.