Mmm. 'Black Death pit' unearthed by Crossrail project is almost one of the subplots in my novel, Roman DNA.
Over a dozen year period, black death killed between 75 and 200 million people. Although anthrax has also been proposed as the culprit, most now believe the yersinia pestus bacterium pictured on the left was the cause.
Wikipedia adds that we now know that the bacterium originated in rodent populations in China. There are two documented cases of y. pestis being used in warfare. In 1347, plague victims were catapulted over the walls of a city. In World War II, a Japanese plane released the plague over a province in China.
Back to the BBC article. It is believed this burial occured early during the black death because the victims were neatly buried in rows. As the plague worsened, there are graphic descriptions of the bodies just being piled into mass graves.
Scientists and archeologists are excited about the discovery. They hope to recover DNA from the human skeletons, possibly samples of the bacterium that nearly destroyed the world, and general knowledge of the people during the black death.