Barrage Vauban
You begin on top of a fortification that looks, at first glance, like a long stone bridge with a lawn on its back. The Barrage Vauban stretches across the Ill on thirteen arches, and from the panoramic terrace on its roof you look straight at the towers of the Ponts Couverts, the half-timbered houses behind them and the cathedral rising in the background.
The plans came from Vauban, who judged the spot where the Ill flows into the historic centre to be a weak point in Strasbourg's defences. Artillery had outgrown the medieval covered bridges, so between 1681 and 1688 the engineer Tarade built this new barrier about a hundred metres upstream of them. Over time it collected names: the Great Lock, the flour lock, the casemate bridge.
The trick was water, not walls. In an attack, iron panels would seal all thirteen arches, the Ill would back up, and the fields and orchards south of the city would turn into a swamp where enemy troops were meant to get stuck. It was actually used during the siege of 1870, flooding the districts upstream. Afterwards the German authorities added a storey and covered the whole structure in earth and turf, which is why it looks so green today.
In 1966 the city opened the roof terrace, and the barrage has been a listed historic monument since 1971. Give it a few minutes: if you want the postcard view of the covered bridges, this is where you get it. It's a different view from the cathedral platform, which looks out over the rooftops towards the Black Forest and the Vosges.
From here it's 510 m, about 7 minutes, into Petite France, the half-timbered district on the river, where the Maison des Tanneurs waits.
