NEW YORK • When the world was given a pre-opening peek in 1966 at the building designed by Marcel Breuer on East 75th Street and Madison Avenue, the then new home of the Whitney Museum of American Art, the ceremony was nearly cancelled because of a bomb threat, one that would have sent luminaries such as former United States first lady Jacqueline Kennedy and Mayor John V. Lindsay into the streets.
On Tuesday, the Metropolitan Museum of Art formally reintroduced the building as the Met Breuer, its new brutalist outpost for modern and contemporary art, and the gathering was an altogether quieter affair.
The only bombshells were on the walls: Leonardos, Titians, Rembrandts and Turners that at first glance looked so strange amid the Breuer's trapezoidal windows and glowering-grid ceiling coffers that they seemed to be parts of a conceptual work devised by a wry contemporary artist - maybe Jeff Koons, who collects old masters and was the subject of the Whitney's send-off to the space in October 2014.
But Met curators and officials, present for a media preview of the building, described this sense of dislocation as gratifying for an encyclopaedic museum, especially one that has long struggled to bring the masterpieces of the last century into conversation with those from the preceding five or so millennia.
Mr Thomas P. Campbell, the Met's director, called the move - first proposed more than eight years ago by Mr Leonard A. Lauder, then the Whitney's chairman, as a way of "keeping the lights burning" - not only a turning point for the Met, but also "a significant moment for the city".
"This is a masterpiece of mid- century architecture and we're going to be reactivating it with a new curatorial spirit and re- weaving it in new ways into the cultural fabric of New York City," he said, standing on the museum's garden level, at the base of what critic Ada Louise Huxtable once described as the building's "disconcertingly top-heavy, inverted pyramidal mass", a shape that grew on one only slowly, she added, "like a taste for olives or warm beer."
But the building - which the Met has leased from the Whitney for eight years and which opens to the public on March 18 - has long since taken its place within the city's architectural DNA.
And in deciding how to reinvent it for a new museum and a new age, Mr John H. Beyer, a founding partner of Beyer Blinder Belle, the architecture firm that restored the building, said most of the decisions involved simple, originalist steps backwards, to Breuer's intentions.
The bookstore was removed from the northern end of the lobby to open up the floor so visitors immediately sense the broad span between the museum's load- bearing walls.
A partial wall concealing the guts of the old automated coat rack was also removed, Mr Beyer said, "because that coat rack was as much a part of Breuer's design as the architecture - he loved it; it was new technology".
The building's few basic materials - concrete, granite, bluestone pavers, bronze for handles and railings and elevator doors - were taken almost back to their elemental states, with only a low-sheen wax applied to the floors.
The wood railings were stripped of varnish and finished with Danish oil, as Breuer specified, so that they exude texture that the architect described as being "close to earth".
The rough, bush-hammered concrete walls, which reveal the black obsidian stones used in their making, were only cleaned and holes in them were plugged, sometimes with obsidian, to mimic the texture around them.
"He loved the hard dignity of ageing materials," Mr Beyer said. "One of the most important parts of restoration is in deciding what not to do. And we didn't do a lot. But what we did, I think, gives you a clear understanding of the space as he created it."
In preparing the exhibition that fills the museum's third and fourth floors - Unfinished: Thoughts Left Visible, which examines, over more than six centuries, the idea of what constitutes a completed work of art - curators from Met departments worked together for months to fill Breuer's art-friendly spaces with works made by both the living and the very-long dead.
"One of the things that's been so thrilling for us," said curator Andrea Bayer, "is to see how different our own paintings look here and the effect is hard to understate."
Many, particularly from the Renaissance, stand up to Breuer's unforgiving materials and grids "in a very muscular way", she said - and one that underscores how much of the contemporary sculpture in the show "draws a straight line all the way back to Michelangelo".
Painter Kerry James Marshall, who was in the crowd on Tuesday, said that no matter how much his contemporaries might want to deny or push against it, "on some level", they "want to be a part of an institution like the Met".
"Artists make art because other artists made work that inspires them," said Marshall, whose retrospective will come to the Breuer in autumn. "But at a certain point, just coming to the museum to see what other people did in those spaces is unacceptable."
For himself, he summed up, exultantly: "I can finally say that I've been in an exhibition with Leonardo da Vinci."
NEW YORK TIMES