The whole crossing runs 963 metres, of which the arch span itself accounts for a little under 249. The arches rise 45 metres above the deck. The deck rides 22 metres above the water, high enough for shipping to pass beneath without ceremony. Twenty-one metres of width sound generous until you divide it: six metres go to Deutsche Bahn for a single track of the Lübeck-Puttgarden line, and the remainder handles two lanes of road traffic and a walkway. Construction began in 1958. The design team worked at Gutehoffnungshütte Sterkrade AG in Oberhausen, under chief engineer Helmut Wild and with engineers G. Fischer, T. Jahnke and P. Stein; the architect Gerd Lohmer was brought in for the look of the thing, and it shows.

Look closely at the hangers and you notice they are not vertical. They lean, crossing one another in a diamond mesh between arch and deck. This is a network arch, a form the Norwegian engineer Per Tveit had worked out only in the late 1950s. Crossing the hangers spreads load along the arch instead of concentrating it, cutting bending moments under uneven traffic and stiffening the arch against buckling — worth up to twenty per cent of the steel a conventional arch of the same span would need. Fehmarn's was among the very first ever built, opening the same year as another early network arch at Steinkjer in Norway. The clothes hanger was a prototype that happened to also be pretty.

The bridge existed to serve the Vogelfluglinie, the bird flight line, so named because it traces the migratory route between Hamburg and Copenhagen. Before 1963 the journey involved a ferry across Fehmarn Sound and a second, longer crossing from Großenbrode Quay to Gedser in Denmark. On the day the bridge opened, both were rewritten. The Fehmarn Sound ferry simply stopped, and the long Gedser run was replaced by a much shorter hop from Puttgarden on Fehmarn to Rødby on Lolland. Road and rail traffic between the two capitals of the region saved hours in a single stroke. The island, until then a quiet agricultural place reached by boat, found itself on the main line to Scandinavia.

This was 1963, and the road it carried led straight to a NATO frontier with the Warsaw Pact across the water. So the mainland approach was built with six explosive vaults set into the ground beneath it, wired to a control point about a kilometre inland at Heinrichsruh, ready to drop the approach ramp if an invasion came. The vaults are long since disarmed. Their positions are still perfectly obvious to anyone who knows to look: six square patches of asphalt in the surface of the approach road, slightly different in colour from everything around them. Cars pass over them at a hundred kilometres an hour without a thought, which is the most cheerful thing that can be said about a Cold War demolition chamber.

In 1999 Schleswig-Holstein's heritage office listed the bridge as a historic monument, citing its significance for the history of technology and its effect on the cultural landscape. That protection is about to become load-bearing in a new sense. The Fehmarn Belt Tunnel is under construction between Puttgarden and Rødbyhavn, and the traffic it will unleash is more than this crossing was built to carry — a 2012 study said so plainly. In 2020 the decision came down to build a second Fehmarn Sound crossing, a four-lane, double-track tunnel, and hand it the through traffic. The bridge stays. It keeps a lane in each direction, its single track, its walkway, its cyclists and its islanders. After sixty years as the only way onto Fehmarn without a boat, it gets to become a local road with a very good view.