Right in the city centre, the construction of a 4 km long North-South light-rail tunnel between 2004 and 2010 means digging in an area of 30 km2. This spawned the biggest archaeological project ever in Cologne [20], while construction costs skyrocketed. Science determines the pace of construction here, and a team of up to 100 scientists and technicians has unearthed many archaeological artifacts from the city's Roman history, including a 2000 year-old wreck of a Roman freight ship and the remains of Roman wharfs [19].
Mit der U-Bahn in die Römerzeit. Ein Handbuch zu den archäologischen Ausgrabungsstätten rund um den Bau der Nord-Süd-Stadtbahn. KiWi, 2006. (In German)
S-Bahn (suburban metro)