New pavilion gets you hot under the collar

The unveiling of the Serpentine Pavilion (now in its 10th year) has become as much of a summer fixture as Henley. And yet it is not without controversy. Why, for instance, does the Serpentine Gallery in London insist on commissioning global stars such as Frank Gehry and now Jean Nouvel when it could be giving up-and-coming architects much needed exposure? Its original remit was to show architects who had not yet built on British soil, but though this has held true for eight of the 10 commissions, it certainly wasn't true of Gehry (who had built a cancer unit in Dundee), nor now of Nouvel: his One New Change, a shopping and office complex right next to St Paul's Cathedral, will be unveiled in the autumn. Other commissions have been by equally illustrious figures.

Still, it's a site for experimentation and, whether you like it or not (and many critics resolutely don't) Nouvel's design is certainly experimental. Made up of jutting geometric planes that feel as if they might topple down at any moment, the Pavilion is made up of a steel structure, plastic cladding, retractable roof flaps, a giant awning and giant glass walls. It is not what you might call "organic" - it's only unifying feature is that the whole thing blazes in fire-engine red. In fact, everything inside is red, too, including the seating and the row of Smeg fridges near the bar.

But though it doesn't exactly feel light and summery, summery pursuits are on hand: you can play table tennis, relax on bright-red mattresses, swing on a giant hammock, or play a game of chess on one of the chessboard tables. You might just not want to spend too long in its slightly claustrophobic, womb-like interior when the sun is high and blazing.

And if you feel that all that red has raised your temperature and your heartbeat, you might want to visit Christian Boltanski's white booth nearby. Inside Boltanski's Les Archives du Coeur (The Heart Archive) you will find two assistants in white lab coats. In a sobering meditation on mortality by the French artist/archivist, they are on hand to record your heartbeat for posterity. The recordings will eventually form part of a permanent installation on Teshima Island in Japan's Seto Sea, and visitors will also be given a "limited edition" recording.

• Jean Nouvel's Serpentine Pavilion at Kensington Gardens, London W2 until 17 October
• Christian Boltanski's Les Archives du Coeur until 6 August
• See Frank Gehry's 2008 Serpentine Pavilion