Archaeologists on the London Crossrail project say they have already found a section of Roman road, a 400-year-old gold coin and the bodies of plague victims. The project involves the digging of 26 miles of new rail tunnel under central London. It is the biggest infrastructure project underway in Europe, and the archaeological dig accompanying it is the largest of its kind. Archaeologists are working on the site of q cemetery that opened in the 17th century, the first in the city not associated with a parish church, The Guardian reported Wednesday. It was on the ground formerly occupied by the notorious Bethlem asylum, which has come down in the English language as bedlam. . \"Because of its history, we know that this is one of the most diverse burial grounds in London, a real cross section of its people across two centuries,\" Jay Carver, Crossrail\'s lead archaeologist, said. \"Bone preservation is excellent in the finds we have already made, and we are expecting many important discoveries when we get into the main phase of the excavation.\" The coin, originally from Venice, was probably sewn to a garment, archaeologists say. Presumably a loose thread led to its loss and eventual rediscovery. The Roman road shows the work of ancient engineers. It crossed a section of bog with a bottom layer of brush, topped with more layers of material and topped with a surface of gravel and rammed clay. Crossrail, which will link some of the rail lines that now have their terminus in London, is scheduled to be completed in 2018.