Trier

World-heritage Trier its considered Germany's oldest city. It was one of the leading centres of the Roman empire in the 3rd and 4th centuries and the remains of a Roman hall, walls, the monumental Porta Nigra gateway, bath complexes and an amphitheatre survive.

The great Romanesque cathedral of St Peter and the delicate Gothic Liebfrauen-Basilika are the most prominent of the city's medieval buildings. But there are also restored town houses, the Marktkirche St Gangolf and an early tower-house built of rubble from the early Roman walls.

It's possible to stroll through the levels of the vast Kaiserthermen bath complex, the Porta Nigra and the amphitheatre to see how this northern Roman city worked. The Rheinisches Landesmuseum displays other Roman remains, including colourful mosaics and the painted replica of a towering grave column. A model shows what Roman Trier, much bigger than the medieval city, looked like.