Frankfurt (Main), a financial hub, is renowned for its skyline, the Römer, and the Städel Museum. The journey begins at Frankfurt Hauptbahnhof, leading you to Aachen, known for its stunning cathedral and historic significance as Charlemagne's favorite residence. Arriving at Aachen Hauptbahnhof, you can explore the city's thermal springs and the UNESCO World Heritage Site of Aachen Cathedral, a true architectural wonder.