Luxembourg was developed as a city from the 16th century in a strategic position on the tri-border with current-day Belgium, France and Germany. Its protective walls were not taken down until the late 19th century and was one of Europe’s greatest fortified sites until that time. The city-state was constantly reinforced as it passed between European powers: The Holy Roman Emperors, the House of Burgundy, the Habsburgs, the French and Spanish kings, and finally the Prussians. Until their partial removal in 1867, the fortification walls of Luxembourg were a prime example of military architecture that spanned several centuries. The Moselle River comprises a long portion of the southeast border with Germany and although Luxembourg City is not directly on the Moselle, it is a short drive from one of your cruise ports making for the perfect excursion.