Cologne Cathedral was built to house the relics of the Magi. The story goes that the relics were stolen by Frederick I also known as Frederick Barbarossa ("Redbeard") in the 12th century and brought to Cologne. While this is a much visited site the line to enter was not long. The relics are in the back of the Cathedral housed in a golden sarcophagus (wood covered with gold and silver). It is decorated with more than a thousand jewels and beads. Less noticed is a portion of the old Roman north gate to the left of the new entrance dating back to 50 AD. Easy to visit though there are a few steps to get up the the Cathedral. If time allows daily services are held that the public can attend. Times vary so check the schedule.