The gun rooms
Embrasures aimed to cover set angles of the slope.
GilPe — CC BY-SA 4.0 · GilPe — CC BY-SA 4.0 · GilPe — CC BY-SA 4.0 · GilPe — CC BY-SA 4.0
The Pétrusse Casemates are the second network of military tunnels beneath Luxembourg, and they differ from the Bock casemates in place, date and engineer: these run under the Place de la Constitution to the west, cut into the cliff of the Pétrusse valley by the Spanish from 1644 and later extended by the French under Vauban. The defensive logic is plain inside them: passages sloping through the rock connecting different levels, gun rooms with embrasures onto the valley, narrow stone stairs and ventilation shafts. These were not stores but fighting positions — every opening aimed to cover a particular angle of the slope below. The practical difference from the Bock is that these are visited by guided tour only and on far fewer dates, often in the summer months alone. The compensation is that they are much quieter: a small group with a guide explaining, rather than the continuous queue at the Bock. With time for one, choose the Bock; with time for both, this completes the picture.
Embrasures aimed to cover set angles of the slope.
A small group and explanation, not a queue.
Place de la Constitution, 1468 Luxembourg
The Stierchen BridgeThe Stierchen is a small stone bridge crossing the Alzette in the Grund, and clo1 minute walk4.9
The Bock CasematesThe Bock Casemates are a network of tunnels cut inside the rock beneath the old 1 minute walk4.5
The Castle BridgeA short stone bridge linking the upper town to the Bock promontory, and the only2 minutes walk4.6
The GrundThe Grund is the quarter in the valley floor directly beneath the upper town, on3 minutes walk
Neumünster AbbeyNeumünster Abbey is a broad white complex on the floor of the Grund valley besid3 minutes walk4.5The Bock, without hesitation. It is the larger and the more visually striking, entered freely without booking or a guide, open across the season, and its embrasures look directly over the Alzette valley and the Grund. The Pétrusse casemates are smaller and need a guided tour on few dates. Plan the Bock first and add the Pétrusse only if you happen on an available tour.