Trier is the city that Germans call the oldest in the country, and the Barbara Baths are among the reasons it can say so with a straight face. Built in the second century AD, when Augusta Treverorum was one of the leading cities of the Roman north, they were once among the largest bathing complexes anywhere outside Rome, a vast rectangle of hot rooms, cold plunges, exercise yards and furnace tunnels. Later centuries treated the building as a quarry, and medieval Trier built houses and a monastery over parts of it, which is why what survives is a maze of walls, arches and basement passages rather than a roofed hall. Walk down into the underground service tunnels and you can see the sooty vaults where slaves tended the fires.
The ruin is right in the south of the old town, within a short walk of the Roman bridge and the amphitheatre, and it forms part of the Roman monuments of Trier that were listed by UNESCO in 1986 along with the Porta Nigra, the Basilica of Constantine and the cathedral. Spend a morning with all of them and you understand why Constantine liked the place.
For a rider, Trier is a joy because of what surrounds it. The Moselle winds west and northeast through steep vineyards, and the road along the river, with its long smooth bends, castles on the ridges and wine villages every few kilometres, is one of the best slow rides in Germany. In the other direction the Hunsruck and the Eifel give you forest roads, climbs and more demanding twisties. Fuel is plentiful in a city of a hundred thousand, and Luxembourg is only a short ride away, where petrol is often cheaper.
Riesling is the wine here, grown on slate slopes so steep that harvest is done by hand. Stop for a glass in a village on the river and plan to sleep over. The city also claims Karl Marx as a native son, with his birthplace now a museum.
April brings blossom on the slopes, September and October the harvest and the golden colours. Summer weekends are busy. Winters are grey but cheap and quiet, and the Christmas market under the Roman gate is excellent.