If you're lucky enough to be travelling to London before October 16 (or if you're living there), we highly recommend you visit this year's Serpentine Gallery Pavilion, by the Swiss architect Peter Zumthor.

From the outside, as you can see in the image below, it's an inscrutable black timber box. We haven't been able to work out what the timber is coated in, but it had a thick, hand-applied quality that lent an artisanal feel to the structure's exterior. 

There are three door-sized holes in the pavilion's exterior. Visitors can pass through any of them (entry is free). You then arrive in a dark, narrow corridor leading to other openings.

Once you've passed through these secondary doorways, you'll find the small miracle of a courtyard garden with planting designed by Piet Oudolf, the Dutchman who also had a hand in the planting on New York's High Line (along with a lifetime of fascinating projects (which you can read about here).

Zumthor's black walls throw Oudolf's pretty planting into sharp relief. It's a deeply contemplative space, surrounded by benches and tables and chairs with a view of the garden and the slice of sky above. On the way there, we'd wondered about the wisdom of Zumthor designing a garden space in the middle of Kensington Gardens, the enormous green space where the pavilion is located. But the courtyard garden works beautifully as a contrast to the open spaces outside, enhancing the appreciation of nature by confining it to this small space.

The modest but magnificent simplicity of Zumthor's pavilion is apparently typical of his work (we haven't had the good fortune yet of seeing any other structures by him, but many of you will know of the Thermal Baths at Vals, which you can see more of at the link here). His structures are rich in texture and materiality, but also inherently modest in their approach.

Each year the Serpentine Gallery commissions an architect who has not previously had a project built in the UK to design a summer pavilion in its grounds (the pavilions are auctioned off at the end of each season). Zumthor's pavilion is an interesting, self-assured contrast to the architectural fireworks of some of the projects of previous years. You can see a slideshow of previous Serpentine Gallery Pavilions on The Guardian's website at the link here.