Atlantic utopia.

Growing on the flanks of a volcano in Tenerife is an idealistic garden in which art and landscape are fused to generate an atmosphere which attempts to foster humanist and ecologically conscious thought.

The Canaries, the Fortunate Isles of myth, lie about 100km off the southern coast of Morocco just above the Tropic of Cancer. They enjoy a hot and usually dry climate tempered by the surrounding sea. But their spiky volcanic peaks sometimes attract clouds and rain softens valleys in the stony slopes with patches of bright green vegetation. Being ruled by Spain, their inhabitants have long mastered the arts of irrigation, and the landscape varies from sloping semi-desert to lush groves of bananas and oranges, and intensive passages of vegetable cultivation.

In 1984, Helga and Hans-Jurgen Muller, German gallery owners, conceived the notion of what they called their 'Atlantis Project', which is intended to bring artists, scientists, businessmen and politicians together to try to encourage new humanist and eco-conscious ways of thinking. The site is at Arona, on the south-western slopes of Tenerife, far from the major tourist centres, with marvellous views of the mountain landscape and out over the sea. With immense persistence, they promoted their ideas, and inspired many well-known people to support them, from the Dalai Lama to the distinguished former German President, Richard von Weizsacker. By 1985, they were able to ask Leon Krier to design the Atlantis Project. Later, Frei Otto advised that plans should be reduced in ambition, and a smaller version was generated: it was called 'Mariposa' - 'butterfly'.

Now, its buildings straggle irregularly along the top of a slope which falls (quite steeply in places) towards the sun. In the garden itself, buildings are quite small, usually unicellular affairs, made with traditional materials: for instance random rubble walls rendered in colour and roofed by thatch or local tiles. But the power of the place is not in the buildings themselves, but the way in which they relate to each other, and to the landscape. Arranged to take advantage of views and incidents of topography, the garden is a net of episodes and events: you see the sea there, the mountain behind, the pointy hills framed by an opening, a vista terminated by a tree. The only major gesture is a long stair path which wanders down from the acropolis at the top of the slope: this Escalera Dorada, Golden Stair, descends into the stony landscape.

The picturesque atmosphere is greatly enhanced by pieces contributed by many artists (including the Mullers). They provide many memorable events, which range from small things like coloured glass marbles set in a strip in the floor of a court, or a little birdhouse on a stone column by Alexander von Branca, to a much larger and rather worrying tepee-like object thatched in long local pine-needles by Fernando Villaroya and Ulrike Theisen which stands as high as a person propped against a wall, or the strange Roter Platz (Red square): an oval place paved in rough red stone with a white pebbled pool in the middle, fed by a little artificial spring.

Throughout, there are interactions between art and nature: a fig tree's trunk and branches are painted bright blue. (Is this ecologically correct? at least the tree puts out leaf.) That rather curious metallic-looking little prickly pear turns out to be a sculpture by Hans-Jurgen Muller, set next to the real cactus. Elsewhere, another has been strangely cultivated so that a prickly person emerges.

Underlying the whole garden is the stony mountain slope, sometimes formally terraced, sometimes allowed to appear almost natural with thin shards of slate heaped up, or slopes of scree carefully modulated in size and colour, or cemented together to make paths. Planting is partly traditional, with pines, palms, aloes and cacti, and partly rather more modern with, for instance, eucalypts (is this a good idea in the northern hemisphere?). Down the Golden Stair, terraces are covered with prostrate junipers and other such low-growing mats punctuated by cactus. Here and there, those delightful but very spiky spherical cacti seem to get a life of their own, planted in straight lines to divide a terrace like a row of hedgehogs on parade, or clustering like a small animate herd at the edge of a stream.

Tenderness for the natural and human world runs throughout the garden. Sometimes events seem a bit kitsch and twee, but on the whole, the place sensitively lives up to its ideals and generates an atmosphere in which they are enhanced.