When people say Trier is the Rome of the north, they mean it more literally than you might think. For about a century, from the late third to the late fourth century, the city was one of the seats of the Western Roman Empire, a place where emperors lived and ruled, and the Romans left a collection of monuments that is among the best north of the Alps. UNESCO listed them in 1986, and the group includes the Porta Nigra, the amphitheatre, the imperial baths, the barbarathermen, the Aula Palatina, the Roman bridge, and the cathedral's Roman core. Some stand in the centre, others on the edge, and a good plan is to walk between them with a map.
The Roman bridge is a favourite of mine. Its stone piers date from the second century, and although the upper parts have been rebuilt, it still carries traffic across the Moselle, which makes it the oldest bridge in Germany still in use. Upstream, at Igel, a tall sandstone column covered in carved reliefs, the Igel Column, was set up by a family of wealthy cloth merchants as a family tomb monument, with scenes of trade, farming and banquets that give a picture of daily life in a Roman province.
For a motorcyclist, Trier's old city has restrictions, so the bike is best left at a car park at the edge. The Moselle valley road is a classic, running along the water between vineyards, with castles on the ridges and villages of half-timbered houses, and the surface is generally good. Be careful on the narrow sections in towns, where parked cars and delivery vans can block the way, and watch for slippery wine-slate on the verges in autumn.
All the services of a hundred-thousand-strong city are on hand, with fuel on the ring roads and supermarkets close to the centre. The best lunch is a plate of local sausage, Riesling and a pretzel in a courtyard in the old town.
Spring and autumn are the finest seasons, and in December the Christmas market under the Porta Nigra draws crowds.