At the end of our trip, we stopped off for a day in Luxembourg and
visited Luxembourg City, which turned out to be a very pleasant place
to spend a day.
It is a very old city, with a river valley running right through the
middle of it - all along the river valley there were fortifications
built up over the years, parts of which were still being used even
during WWI. The fortifications were so strong, combined with the
ability to dam the river and flood the valley, made the city quite
formidable, to the point where it was never conquered (however, due to
politics in far away lands, it seemed to change owners quite
frequently.)
Here is a view of the Eastern side of town, looking over some of
remaining casemates etc.
Two views of the valley - on the left, overlooking the valley (see the
arched bridge in the background), on the right, a view from the bottom
of the valley, looking up at the arched bridge.