Trier claims to be the oldest city in Germany, and it can make a respectable case. The Romans founded it as Augusta Treverorum around the end of the first century before Christ, and by the fourth century it was one of the capitals of the empire, a city of emperors, with palaces, baths and a circus. Constantine the Great lived here for years before he moved east, and the city's buildings from this period are so impressive that UNESCO lists a group of them together with the cathedral and the Church of Our Lady.
The Porta Nigra, the Black Gate, is the icon. It is a huge fortified city gate of massive sandstone blocks, built in the second century and darkened by time into a deep grey. In the Middle Ages a monk named Simeon lived in it as a hermit, and a church was built into the structure, which saved the gate from being dismantled for building material. The Basilica of Constantine, with a vast brick hall, is still used as a church, and the Imperial Baths, which are the ruins of an enormous complex, show how the Romans liked to bathe on a grand scale. An amphitheatre on the hillside once held twenty thousand spectators. In the narrow cobbled streets of the centre, the Hauptmarkt is the pleasant heart of the city, with a market cross and old houses.
Trier is also the birthplace of Karl Marx, born here in 1818 in a house that is now a museum. The city lies on the Moselle, in a valley of steep vineyards producing some of the best Riesling in the world, and the Moselle road is a classic ride, a series of long bends following the river through villages and terraces of vines, with castles on the heights. Spring and autumn are the best seasons. In summer, the road fills with campervans and cyclists, so start early.
Luxembourg lies only about ten kilometres to the south-west, and many riders cross the border to take fuel, which is cheaper there. Trier itself, with about a hundred thousand people, has everything, from supermarkets to wine cellars. The wine is white and crisp, and the local food is hearty, with sausages, potatoes and cheese. The best way to see the monuments is on foot, because parking in the centre is limited and expensive. A short ride to Völklingen, across the border in Saarland, takes you to the ironworks, another UNESCO site and a monument of a different age.