First look inside the Tate Modern's new extension

The extension has been an opportunity for the museum to reorganise its permanent collection across the galleries in the original building (now called the Boiler House) and those in the Switch House. Seventy-five per cent of the works on display in the new building have been acquired since 2000, and the collection now encompasses art from beyond Western Europe and the US.

It also includes work in interdisciplinary practice that spans dance, photography, film and installations, as well as traditional media. “The whole raison d’être of the Switch House,” explains Morris, “is to look at the point since the Sixties [onwards] when art became active and artists began to ask more of their audiences.”

This means that barriers around works are largely absent. Displays have been moved out of vitrines and works on show include Hélio Oiticica’s Tropicália, complete with a live caged parrot, and a table from performance artist Marina Abramovic’s 1974 piece, Rhythm 0, displaying objects she invited the audience to use on her — a feather, honey, scissors and nails.

Compromises are necessary when an art museum wishes to cover all the bases. Both daylight into the galleries and views from them are limited by the conservation needs that come into play when a museum wants to display the gamut of a contemporary artist’s practice in a single space, from canvases to more fragile photographs and works on paper. Hence even where skylights are possible, such as in the Level 4 room, they will be covered on opening to control light levels.

Hal Foster, the American art critic and author of The Art-Architecture Complex, has been critical of museums that resort to novelty architectural branding. He questioned institutions that grow on the back of a desire for the broadest audience, resulting in a lack of character to their generic galleries. But no other museums were harmed in the making of Tate Modern, and while the Switch House’s architecture is crowd-pleasingly dramatic, this is not pointless “starchitecture”. Instead it is a clever response to the site and the needs of a national collection to broaden and update: “Art Changes We Change” has been Tate Modern’s slogan for the project.

In this case, bigger really is better. Better than the existing museum building, where galleries can sometimes be gloomy and circulation tortuous. Herzog & de Meuron created the original Tate Modern at the outset of their career and in the years since 2000 they have learned to build museums worldwide that successfully marry adventurous architecture to good hanging space. Tate director Sir Nicholas Serota argues that it is unprecedented for a museum to employ its original architect for a later extension. Revisiting Bankside has given the architects the chance to graft new thinking onto old stock. The scabbed concrete of the “as found” spaces approaching The Tanks has been extruded upwards with new concrete that is pleasingly raw, while visitor navigation has been improved by devices such as a giant internal slot uniting each of the gallery floors (echoed in miniature by open slivers either side of the treads on upper staircases). The effect of the concrete has been softened by matching it with joinery, such as the elegant timber bench that runs around the edge of the new members’ room: “The most important challenge was to make it all feel like one building,” says Jacques Herzog. “One thing with different atmospheres but the same organism.”

The new sophistication is evident in the perforated brick veil made up of pairs of specially made bricks joined at the corners by dowels. The entire screen acts as a slightly flexing net, so avoiding the need for ugly expansion joints common to most workaday brick architecture. This is no dumb box and the complexity of achieving the screen has been blamed for the delays — the extension was meant to be complete in time for the 2012 Olympics — and the spiralling costs (from £215 million to £260 million). Serota says not, blaming lack of funds for the project, as well as an expansion of the brief to include a refurb of the Boiler House, as the reason for the cost increase.

The project is not perfect, however. The junction between old and new brickwork is awkward in places and the same dismal Nordic-noir landscaping of silver birches continues on the south side. Here a pointlessly winding path and high garden wall to the terrace above The Tanks means that the opportunity to enliven Sumner Street has been lost. Tate Modern’s immediate setting remains unnecessarily compromised. This is not the “city plaza” that the architects promised.

That aside, the Switch House confirms Tate Modern as one of the world’s most exciting modern art museums in one of the most exciting cities. Look out from its 10th floor at some of the meretricious architectural junk that’s gone up since Tate Modern opened 17 years ago and think what might have been if only architects of this quality had been let loose on more of the capital’s commercial and residential towers.

The New Tate Modern is open to the public from June 17