On June 18, 1815, soldiers from Osnabrück fought under British high command at the Battle of Waterloo. Some served in the city's territorial regiments and its light field battalion. Others wore the green of the King's German Legion, the Hanoverian exile force that had spent a decade fighting Napoleon and that took staggering losses defending La Haye Sainte that long Sunday. When the survivors came home, one of them - Gerhard Friedrich von Gülich, a local doctor of law - decided their courage deserved more than a tavern toast. In 1816 he donated 1,000 thalers to build a memorial. The architrave still carries his dedication in gold capitals: 'To the warriors of Osnabrück who at Waterloo on June 18, 1815 displayed German courage, this memorial is dedicated by G.F. v. Gülich D.R.D.'

Johann Christian Sieckmann designed something architecturally peculiar: a triumphal arch in the style of the Arch of Titus in Rome, with coupled Ionic pillars and a classical platform - grafted directly onto the surviving stonework of the old medieval Heger Tor, which had been knocked down in 1815. From the Altstadt side, walk up to it and you see what looks like an unadorned medieval city gate. Walk around to the outer ring road side and the same structure reveals itself as a heroes' memorial in the classical mode, with echoes of Berlin's Brandenburg Gate in its proportions. The gate is two buildings facing two different directions - a quiet civic gate looking inward, a monument to victory looking outward at the world the war made.

Locals call it the Heger Tor because the medieval Heger Tor used to stand about 20 meters further west - and you can still see the old Akzisehaus, the excise house, marooned on the wrong side of the modern Wallring as evidence. The new arch took the old gate's job and the old gate's name; only the official records remember the Waterloo part. The Heger-Tor-Viertel, the quarter behind the arch, has become Osnabrück's gathering place for the night-time crowd - rustic restaurants and bars threading through narrow streets that haven't moved much since the medieval Heger Tor stood guard over them. In 1957 the city closed the gate to traffic and turned it into a pedestrian passage. A chestnut tree on the platform fell in a storm that November; the trees that replaced it were cleared during the 2013 renovation.

Climb the steps or take the ramps along the wall, and the platform offers the city in cross-section. To the east lies the tranquil medieval Altstadt, traffic-calmed and church-steepled. To the west sits a row of cultural buildings: the Kulturgeschichtliches Museum, the Felix-Nussbaum-Haus art gallery designed for the work of the Osnabrück-born painter killed at Auschwitz, the old Akzisehaus, and the Stüve memorial to the 19th-century mayor who helped negotiate Hanover's constitution. The arch sits like a hinge between two centuries of the city, dedicated to soldiers who fought a battle most of their descendants now remember only because the name is carved on a gate they all call something else.