Try the following tour, recommended by residents or metro enthusiasts:
Explore the diversity of the Cologne Light Rail, going underground (lines 3, 4, 5, 12, 13, 15, 16, 18), elevated (line 13), overland on abandoned railway routes (lines 16, 18 to Bonn; line 7 partly), on roads far out into suburbs (lines 3, 4), on roads using low-floor vehicles (lines 1, 7, 9).
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 , 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 .