In the Middle Ages, Vianden was a fully fortified town, surrounded by city walls with 24 half-round towers and five gates. Most of those ramparts are now gone, taken down by Marechal de Bouffiers in 1679. A few restored ruins and a bell tower remain, however. Take a quick detour via the small stairway between Grand Rue numbers 58 and 60. It will lead you to the 1603 belfry and some nice views over the village.
There's no way to miss the grand castle of Vianden, overlooking and dominating the little town beneath it. It was impressively restored in 1977 and has been a real visitor magnet ever since. A route leads visitors through 20 different historic castle rooms, after passing the modern entrance and soon to be opened visitors centre. Some of the rooms (including the kitchen) have been fully refurbished, in order to give a real peek into life as it would have been in the castle in the middle ages. Others have been restored but leave more to the imagination, including the upper chapel, the impressive Knight's hall and the beautiful Byzantine Gallery. There's an arms room and a genealogy room, where the family history of the castle masters is explained. In short, take your time to wander through these ancient halls. It's a fine trip for adults and children alike.
During his 19 years of exile from France, Victor Hugo stayed in Vianden a few times, most notably for 3 months in 1871. He left behind a painting of the castle ruins as they were at the time and reportedly got the castle architect fired as he thought his work to be insufficient. The Maison Victor Hugo is a small museum displaying some original works (manuscripts and drawings) as well as the original rooms with furniture as the famous visitor has used it. From the museum windows, there's a lovely view of the castle. Audio guides are available in English, French, Dutch and German.
This old church of the Trinitarians is an excellent example of Gothic architecture in the country. It was built as early as 1248, with the large choir originating in 1644. The main Rococo-style altar was created by Michel Weiler in 1758. Adjoining is a small former cloister, from the same 13th century origin. Don't miss a peek in its wonderfully tranquil courtyard. The entrance is a simple door on the side of the building, in the alley between hotel Heintz and the church. Note the late 13th century effigy of Marie de Spanheim.
Musée d’Histoire de la Ville de Vianden
A charmingly small museum, housed in two adjoining buildings on the main street. One of the buildings still has its 19th-century interiors, while the other serves as a bakery museum, with part of the décor of the 1950s bakery that was housed here on display. The house that now has the bakery museum, was once the home of famous poet Edmond de la Fontaine, famous under his pen-name Dicks. A tablet on the façade reminds of the buildings famous former inhabitant. All the text in the museum is in German, but there's an English translation text available on request. The entrance ticket also gives free access to the copper mine museum in Stolzembourg, about 6 km out of Vianden.
If you have a taste for major industrial sights or large water basins, and would like to get away from the crowds, hike a few kilometres up along the river Our, until you reach the Pumped Storage Plant. It has two large reservoirs and was expanded in 2013. The total reservoir capacity is about 10,800,000 m³, making it the largest hydro-electric power plant in Europe. It has a visitors' centre, which allows a peek into its underground power plant. It's a pleasant walk, along the water, but uphill.
Take the 11-min chairlift ride up for a scenic view over town or to spare you a fairly steep hike. To get to the start, follow the Grand-Rue down, cross the river and go left. Follow that street and you'll find it after about 500 m. If you only want to go one way, for logistic convenience it's best to take the lift up and stroll down to the castle and then back to the village. In terms of the view, however, going down it's easier to look around and take pictures. Note that as you go upwards and get close to the exit point, a picture is taken of you, with the Our valley and the town as a backdrop. You can buy a copy for €6.50 as you get out.