The Grand Ducal Palace of Luxembourg. The head of state of Luxembourg has the title Grand Duke, and his palace is called the Grand Ducal Palace. It’s hard to get a good photo of the palace (or to get a good view of it, for that matter), as the street is too narrow to get a shot at some distance from the palace. So I just shot a few details.
Two of those details are worth sharing: A photo of the entrance, and a photo of a guard walking up and down in front of the palace.
The palace, by the way, dates from the 16th century and was originally the town hall of Luxembourg City. Since the 19th century it is the official residence of the grand dukes.