UNESCO World Heritage Site and landmark of Trier. During the excavation of the Roman city wall near the Porta Nigra, antique wood was discovered, which could be exactly dated. The secret has been revealed: Porta Nigra is 1848 years old (2018)! The Roman city gate was constructed in 170 AD. So far, only assumptions were made. The director of the Rheinisches Landesmuseum in Trier, Marcus Reuter, said: "This is a milestone for Trier's city history".