To run trains to Abbey Wood, Crossrail is building a 2.6km tunnel under the Thames between Plumstead and North Woolwich. This tunnel will sit off the main line that goes from Maidenhead in Berkshire and Heathrow Airport through central London, via Paddington and Liverpool Street, along the edge of the medieval and Roman cities, and finally out to Romford and Sheffield in Essex. The paper discusses that the new railway line for Greater London - is more than picking a route and laying track. As Crossrail archaeologists uncover bison bones - and Black Death.