That said, I really enjoyed exploring the ancient tunnels and windowless "rooms" of the casemates. I admit that at first I wasn't really familiar with exactly what casements are--basically, a series of fortified ring-walls that housed thousands of soldiers, horses and various shops throughout the ages. Construction of these casemates began in 963, and the reinforcements which were added in the following centuries by rulers such as the Burgundians, Spaniards, French, Austrians, Germans, etc. earned the strong city the nickname "Gibraltar of the North." In 1867, the military withdrew from the casemates, and although 90% of it was destroyed in the following two decades, enough of the original 23k of tunnels remained to serve as shelters during the two world wars. Today the fortifications have been designated a UNESCO World Heritage Site.

After paying your entry fee (1.50 euros for students, 1.75 adults), you receive a helpful guide/map in English and head to the dark museum-ish upper part of the casements. This "archaeological crypt" includes various displays about the origins of Luxembourg City. The best part is venturing down the various stone stairways and looking out the small windows and bigger openings used for cannons. It's easy to get the feel of how it might have been like to live or work in these passageways since they're so similar to when their construction began a thousand years ago. My best advice to getting the most out of the casements is to go early (the Bock Casemates open at 10am), since at least when I was there it was far busier in the afternoon than in the morning.

Guided tours are required. We had an amazing young man as a guide, who rapidly and fluently switched from English to French to German, delighting all with his historical knowledge and quick wit. The tour requires you to be physically fit enough to climb several flights of steep stairs and maneuver on slippery surfaces.

The grounds around the Casemates are beautifully kept. There is a small train tour available through the property as well.

When we first entered, we paid our entrance fee and were given a map and guide to the Casemates, and then began following the route detailed in the map. This took us past a turnstile, and then were in a long, cool and cave-like room. There was a wooden path built to guide us past an audio-visual show that detailed the history of the casemates. We didn’t spend too much time in this area, and eventually found the path out and a staircase which led down to the heart of the casemates.

At first it seemed like there was no real order to anything, and we just wandered around in what felt like a whole bunch of little caves. But when we both got ourselves organized and actually figured out where we were on the map, it became more interesting. From the audio-visual display room we had descended to the lower cellars of the castle, which offers the first of many really nice panoramic views of the city and the Alzette valley. Moving toward the central passage brought us into the cannon chambers, and directly across was what used to be the castle prison. Turning right and walking to the next little cave yielded the castle well, which is apparently 47 meters deep. Further along the main gallery past this section are the bedroom study and anteroom where a field marshal lived during the siege of 1794-5. We continued in the same direction, and then had to descend down some more stairs, then walk along a short and damp corridor, and then climb more stairs. This area was the demolition chambers, where part of the Bock was blown up.

Then we had to go back the way we came, all the way to where we first entered the casemates after the audio-visual display. We then went past where we first arrived, and saw the other part of the castle cellars. Just to the left was the Ground Battery which was previously used for cannons, but now a small theatre group puts performances on here (I’d like to see that — it looked too small to me). By this point we were basically done with the casemates, and we had to descend another staircase, go through a small and very damp tunnel, and then climb another set of stairs, at which point we were out in the fresh air again.