Archaeologists have begun excavating some 3,000 skeletons from a 17th Century burial ground used during the Great Plague.
The grave at the site of the new Liverpool Street station, which will serve the London Crossrail line, was used as a burial ground from 1569 until 1738 and it is hoped tests on excavated victims will enable a better understanding of the disease.
Lead archaeologist Jay Carver said: "This excavation presents a unique opportunity to understand the lives and deaths of 16th and 17th century Londoners.
"The Bedlam burial ground spans a fascinating phase of London's history, including the transition from the Tudor-period city into cosmopolitan early-modern London.
"This is probably the first time a sample of this size from this time period has been available for archaeologists to study in London.
"Bedlam was used by a hugely diverse population from right across the social spectrum and from different areas of the city."
A team of 60 archaeologists will work in shifts six days a week to remove the skeletons in what could be London's most valuable 16th and 17th-century cemetery site.
They have already found more than 10,000 artefacts spanning many years of London's past across more than 40 construction sites. It is the UK's largest archaeology project.
Preliminary excavations at the Liverpool Street site in 2013 and 2014 uncovered more than 400 skeletons and numerous artefacts.
The Great Plague killed an estimated 100,000 people in 1665-66, nearly a quarter of London's population, and tests on excavated plague victims will further understanding of the evolution of the plague