Fort Dumoulin

The gate and the stretch of wall on the Fetschenhof plateau, out along the road to Trier, belong to Fort Dumoulin, the easternmost work of the fortress and, for a few years, the most modern. It began as an emergency. When the French revolutionary armies besieged the city in 1794 and 1795, the garrison threw up a temporary earthwork here, an arrowhead called a flèche, on a spot the engineers had been meaning to fortify since 1737. A powder magazine was built inside it in 1829, and then, between 1836 and 1838, the Prussians rebuilt the whole thing: a ditch thirty feet deep cut into the rock, casemates proof against bombs, galleries from which the ditch itself could be swept with fire, and an underground passage to the neighbouring Fort Rumigny so that the men could be supplied without showing themselves — with two charged chambers along it, so that the passage could be blown if an enemy got in. It was the first fort of Luxembourg laid out on the polygonal system that was replacing the old star-shaped bastions everywhere in Europe.

In 1843 it was named after Dumoulin, the fortress's first Prussian commandant, and the name wore down in local mouths to "Fort du Moulin", the mill fort, which is why later maps lost track of it. With the neighbouring works it guarded the Rham barracks and the road from Trier; in peacetime, being well outside the town, it was where the fortress kept its powder. Plans to enlarge it were approved in the spring of 1867, weeks before the Treaty of London ordered everything demolished instead.

Its afterlife is the best part. The ruins were sold in 1870 to a veterinary surgeon from Clausen, and from 1885 to 1903 the champagne house Mercier used the bomb-proof casemates as cellars — the same cool, dark, even temperature that suited gunpowder suits sparkling wine. Today the site is the headquarters of the Luxembourg Girl Guides, and the ditch, the gate, the casemates and the passage to Rumigny survive underground, though the passage was accidentally filled with concrete when the national sports institute was built on top of it. It has been on the supplementary list of protected monuments since 2012.