Getting there
Direct trains from Luxembourg Central to Trier Hauptbahnhof run hourly, taking 50 minutes. This trip crosses the border so it costs about $12 each way — free transport ends at Wasserbillig. Buy a Rheinland-Pfalz-Ticket ($28 for a full day of regional trains in the German state) if you plan to explore beyond Trier.
Roman Trier
The Porta Nigra ($5) is the largest Roman city gate north of the Alps and stands 30 metres tall in blackened sandstone. Combined ticket for all Roman sites ($13) includes the Imperial Baths, Amphitheatre, and Basilika of Constantine. The Rheinisches Landesmuseum ($9) holds the largest Roman mosaic collection in Germany.
Trier Cathedral (free) is Germany's oldest church, built on Constantine's palace foundations. The adjacent Liebfrauenkirche is one of Germany's earliest Gothic churches.
Eating and Karl Marx
The Karl Marx House ($6) on Brückenstraße 10, where the philosopher was born in 1818, has been renovated into a solid biographical museum. For lunch, Zum Domstein on the Hauptmarkt serves $14 Roman-recipe dishes reconstructed from Apicius, including honeyed pork. Cheaper: any Imbiss stall around the market for $5 currywurst. Try a Riesling from the Moselle at Weinstube Kesselstatt on Liebfrauenstraße.
Good to know
Is the train to Trier really not free?+
Correct. Luxembourg's free transport ends at the border town of Wasserbillig. Trier tickets are about $12 each way.
How many hours in Trier?+
Six to seven for the main Roman sites, cathedral, and lunch. It's a full day out.
Do I need Euros or does Luxembourg currency work?+
Both countries use the Euro. No currency change needed.
Is Trier better than Luxembourg City?+
Different draws. Trier has heavier Roman heritage; Luxembourg has fortress views. Do both if you have four days.