After a largely non-intrusive flight, where my seatmate and I were in the same mode of "polite but not really wanting to chat", I landed in Luxembourg around 10:30am. The hotel didn't have a room ready, so I left my suitcase and wandered around for a few hours.
Luxembourg city is built around a deep ravine, which I am guessing was based on making it maximally defensible (although I haven't actually looked at the city history in detail yet). It gives the city a remarkable quality, almost like an Escher drawing where there is a lot of interaction between high and low areas. You can also see the mix between medieval fortifications, newer buildings from the 19th century, and brand new construction.
The other impact of the vertical structure of the city that delighted me yesterday was the number of narrow pathways up and down the sides of the ravine, between (again) very old to very new buildings.
And of course in a place where the car is not quite so much the king of the hill, there are accommodations for getting your bike up and down those stairs.