Many of you will have heard of the Black Death, it was one of the biggest pandemics in human history and it was caused by the bacterium Yersinia pestis. Amazingly, we can detect and sequence whole genomes of ancient DNA from the graves of the victims, which enables us to understand the transmission of bacteria 1000s of years ago. The video below describes the recent discovery of suspected plague victim remains during the building of a new train line in London.