Denmark is a country of sand, clay and glacial moraine, which is why Bulbjerg is such an oddity. In 1839 the poet Steen Steensen Blicher called it Jyllands eneste klippe — Jutland's only cliff — and the phrase has stuck for the simple reason that it is true. The rock is bryozoan limestone, built from the skeletons of colonial marine animals and later hardened, and it stands here because glaciers and the sea happened to leave it standing. From the top the view runs west into Thy and east along the great sweep of the Jammerbugt. Bulbjerg belongs to the old district of Hanherred, a strip of north Jutland pressed between the Limfjord and the open Skagerrak, and it is the highest hard thing for a very long way in either direction.

Skarreklit stood about a hundred metres offshore, and the reason it lasted as long as it did was geology rather than luck. Its base was flint — dense, glassy, almost impossible for waves to work — while the softer limestone around it dissolved and crumbled away over centuries. The sea ate the neighbourhood and left the pillar. Eventually even the flint's grip was not enough. At low tide in calm weather the stump is still visible, a dark smudge in the water where a landmark used to be. The name is probably older than any of the legends attached to it: skarv is Danish for cormorant, shortened to skar in the Jutlandic dialect, and klit means dune — though in Jutlandic it can also mean cliff. Cormorant Rock, more or less.

Come in spring and you hear Bulbjerg before you understand it. Black-legged kittiwakes nest on the ledges here — somewhere around five hundred breeding pairs, packed onto a face that would look, to a Norwegian seabird, laughably small. It is nevertheless the only bird cliff on the Danish mainland, and therefore the only place on mainland Denmark where these birds breed. Kittiwakes are named for their own call, a repeated three-note shriek, and several hundred of them delivering it at once off a limestone wall is a sound that carries a long way inland. The birds need vertical rock and nothing else in Jutland provides it. The wider area, taking in the Limfjord broads and the Vejlerne wetlands, is protected as a Natura 2000 site.

Before it was a nature reserve, Bulbjerg was a quarry. For centuries local people sawed chalk blocks out of the cliff to build with, or burnt the stone down to quicklime for mortar and whitewash — a working landscape, not a scenic one. Visitors left their own marks. Names carved into the soft limestone are still legible, left by nineteenth-century visitors who came, looked, and signed the rock like everyone else. The graffiti is now part of the monument, which is a fair reflection of how these places actually accumulate meaning.

The German occupation force recognised what any sailor already knew: from up here you can see a very long way over the Skagerrak. During the Second World War they used Bulbjerg as a lookout and poured a small concrete fortification into the clifftop, which is still there. In the summer of 1996 one of the bunkers was given a second life as a small exhibition on the cliff's geology, birdlife and history — an occupation lookout turned into an interpretation centre, which is a quietly satisfying piece of reuse. The other thing Bulbjerg has, and increasingly few places in northern Europe do, is genuine darkness: it is listed by DarkSky International among its certified dark sky places. On a clear moonless night the Skagerrak below is black, the sky above is not, and the kittiwakes are asleep.