Knud W. Jensen was a businessman in the dairy trade with a serious interest in art and literature. In 1952 he bought the publishing house Gyldendal; he founded an association called Art at the Workplace that leased paintings to companies so employees could live with them. What he could not stand were art museums. The National Gallery of Denmark was his standing example: grand, forbidding, architecturally at war with the work inside it, a building that made visitors feel obliged to approach the art rather than curious to. He wanted a museum at human scale, close to nature, and in 1955 he bought a derelict villa at Humlebæk to build it in — his second choice, after the owners of land near Rungstedlund refused to sell to him on the grounds that modern art was not art.

Jensen first asked Jørn Utzon, who lived nearby at Hellebæk. Utzon was already committed to the Sydney Opera House and declined. The commission went instead to Jørgen Bo and Vilhelm Wohlert, who spent months simply walking the property before they drew anything, and what they eventually designed was less a building than a route: a covered stroll from Brun's old villa out through the park, three low pavilions strung together by glass corridors that bend where the ground bends and stop where a particular tree or a particular view of the Sound deserves a window. The vocabulary is domestic and warm — whitewashed brick, exposed timber, laminated wood ceilings, deep-red tiled floors, and glass wherever a wall would have been a waste. Wohlert had absorbed the wooden architecture of the San Francisco Bay Area and the plainness of Japanese building, and neither reference shouts. You never lose the outside. That is the entire idea.

It opened in 1958 and the reviews were not universally kind. The building had no climate control and not enough storage, faults Jensen freely admitted. The Swedish paper Dagens Nyheter nicknamed it Cirkusiana, on the grounds that a museum also running concerts, films, dance and political debate had stopped being a museum. A Nam June Paik concert ended in chaos and open hostility from the audience. Jensen was unrepentant — art, he said, was never meant to be the whole of it — and the arguments turned out to be the best publicity available. He had budgeted for 40,000 visitors in the first year. Two hundred thousand came.

Louisiana grew the way it was designed to, by extending the walk. Two floors of West Wing arrived in 1966 and 1971. A concert hall followed in 1976, fitted with chairs by Poul Kjærholm and acoustics good enough that Grigory Sokolov, Arcadi Volodos, Emmanuel Pahud and Midori have played in it. The South Wing of 1982 buried much larger, higher galleries in the slope so that international exhibitions could be staged without the building getting taller. Then in 1991 an underground Graphics Wing completed the loop on the east side, and the museum became what it now is: a rough circle drawn around a park, so that you leave by arriving back where you began. A three-storey Children's Wing followed in the later 1990s. Every phase kept to the same rule — stay low, follow the terrain, do not compete with the trees.

The park slopes from a plateau down toward the Øresund, thick with old specimen trees, and the sculptures are placed through it rather than in it — some in enclosed yards visible from indoors, some standing alone on the grass with nothing behind them but water and, on a clear day, the Swedish coast. Arp, Ernst, Max Bill, Calder, Alicja Kwade, Laurens, Miró, Henry Moore. Indoors the collection runs from the end of the Second World War forward: Giacometti, Bourgeois, Picasso, Warhol, Rauschenberg, Asger Jorn, Kiefer, Richter, Hockney, and Yayoi Kusama's mirrored installation Gleaming Lights of the Souls, on permanent display. Some works were made for the place — Roy Lichtenstein painted Figures in Landscape in 1977 after visiting, and Sam Francis produced a series here in 1979. Louisiana now takes more than 700,000 visitors a year, the most of any museum of modern and contemporary art in Scandinavia, runs six to ten exhibitions annually, hosts a literature festival every summer that draws forty writers and fifteen thousand listeners, and since 2012 has published Louisiana Channel, a free video archive of artists talking that has become among the largest of its kind anywhere.