The Metropolitan Museum of Art, which opens a new outpost in Marcel Breuer’s iconic former Whitney Building in Manhattan next week, is a rare building tenant with fewer demands than the original – a triumph for Breuer’s structure and any who will have the chance to visit it.

Thomas Campbell, director of the Met, described the 1966 building as a ‘great sculpture in its own right’ at the preview yesterday. This work of art – rechristened The Met Breuer – underwent a comprehensive restoration for its new incarnation as a space dedicated to displays of the Met’s contemporary collection.

Breuer’s building is a landmark of concrete Modernism (if shockingly not an actual New York historic landmark). It is usually described as a ziggurat, and most colourfully, by architecture historian Isabelle Hyman, as a ‘beetle-browed Cyclopean’.

Despite its imposing, bunker-like form, it offers a surprisingly cosy museum-going experience. Floor plans are modest in size and its rough, bush-hammered concrete surfaces are offset with very precise detailing inside, such as the board-framed concrete that literally frames all walls, teak, bronze, and bluestone – like fine tailoring around rough wool.

The success of the Whitney obscured the simple splendour of its home, as its burgeoning collection and functions strained against its relatively small size. A gift shop cluttered the library, and natural decay and wires spoiled the lines of many walls.

John Beyer, principal at Beyer Blinder Belle, which restored the building, said the Met’s wishes were simple: to accomplish a ‘clarity of circulation’ and ‘a perfect restoration of the building’. He compared his practice’s work to art conservation, their task being the skillful repair and effacement of those accretions that had marred the building’s original scrutability.

‘The building is straightforward in its conception and execution,’ he said. ‘We felt what was important is for that to be better understood.’

Breuer, in his 1963 remarks introducing the Whitney proposal, indicated that the building ‘should transform the vitality of the street into the sincerity and profundity of art’. Beyer Blinder Belle restored its function as an open gesture to the street, while clearing the lobby of extraneous functions and offering ‘a much clearer indication of the way the building was designed’.

An elementary and wonderful contrast has been restored. While the cantilevered concrete floors above are only very selectively fenestrated, the ground floors featured some of the largest glass panels ever placed in New York at the time. These no longer display merchandise, but welcome visitors.

There were many other practical details to tend to, largely concerned with technical elements that had complicated the building’s original simple conception. ‘Endless yards of cabling’ required skillful rearrangement, mainly above the precast concrete suspended waffle ceilings, while hundreds of holes in the walls were filled in and lobby lightbulbs were replaced with custom LED bulbs.

Tending to the state of concrete was at times a more subjective proposition, that of ‘distinguishing between patina (a lovely aspect of any material) and damage’ – a task that is ‘not always so clear,’ says Beyer. This is a challenge familiar to any restoration work. ‘It’s not unlike what we’d do with a classical Beaux-Arts building where we need new infrastructure but it needs to be hidden.’

And hidden it was, leaving nothing to distract from the art within, except for Breuer’s very work of art which houses it.

The Met Breuer opens on to the public on 18 March.