My favorite foreign cache in Luxembourg was GeoWolf 8: A Visit to Vianden, GCJGQF. The cache page says this about the cache:
The hunt will take you from the medieval town of Vianden, dominated by a magnificent castle, to a panoramic view over the Our valley and the location of the largest hydro-electric pumping installation in Europe.
Embedded in the Ardennes, the town of Vianden is tucked at the foot of a restored castle, once owned by the Nassau dynasty, which inherited the county in the 15th century. In 1820, William I of Orange Nassau, King of the Netherlands and Grand Duke of Luxembourg, sold the castle for the sum of 3200 florins to a Vianden merchant who immediately started to dismantle the structure and sell it off in bits and pieces. To calm the anger of the inhabitants of Vianden, William I re-acquired what was left of the castle for the sum of 1100 florins. Today the castle is owned by Government of Luxembourg. Restoration of the majestic manorial seat started in 1977. The halls of the castle are animated by precious gobelins and furniture, ancient weapons and suits of armour. Genealogical tables and portraits still represent the Nassau dynasty.
Here is my log from my find, March 31, 2009:
I am in the area visiting my son who is stationed at Spangdahlem. We went to visit the castle today, then to this cache. The walk seemed a bit long for someone who has done a LOT of walking in the past week, so my son took it upon himself as a challenge to see how far he could get on the roads. (They weren't what I would classify as roads but his Blazer got through.) We were able to drive to within .3 of the cache, then took a nice hike the rest of the way and found the cache easily. Beautiful view from the cache area! I left two travelers, one that wants to go home to Germany and another that wants to go to Switzerland. We're almost to the border here and I'm not sure if I'll find another cache big enough for the car so left them both here. Thanks for the opportunity to find a Luxembourg cache! #1509 RedhedMary from Michigan, USA
Though my Air Force son is not a geocacher, he took me here and helped find the cache. That adds to the memories!
This cache is hidden at the Wittenbach/Wege Nature Center. It may be more muggle-prone than most as it is off the main trail. Be discreet!