The rust Pavilion

An ellipsoidal mushroom cultivation pavilion at Casa Wabi in Oaxaca is designed to rust, change, and eventually become part of the landscape.

OMA's Mushroom Pavilion at Fundación Casa Wabi, the art and community campus founded by Mexican artist Bosco Sodi on a sixty-five-acre stretch of Oaxacan coast between the mountains and the Pacific, is made from troweled concrete poured in situ, with burlap stamped on the exterior to retain the site's high iron content water. Over time, as the natural conditions of the site act on the material, the pavilion will rust and change in appearance. This is not a design flaw. It is the design.

The project marks OMA's first built work in Mexico, designed by partner Shohei Shigematsu, and it does something unusual with an unusual brief: mushroom cultivation. The ellipsoidal form — dome-shaped, stepped, two hundred square metres — was optimised entirely around the specific requirements of growing mushrooms while simultaneously creating a space for people to gather. Inside, the domed volume is divided into three chambers surrounding a central space: a fruiting room, an incubation room, and a storage room. The lower half of the interior is stepped like an amphitheatre in the round, its shelves holding handmade terracotta mushroom pots crafted by local artisans. The stepping and the elliptical geometry create a panopticon viewing experience — the entire cultivation process visible from any point in the space."As a Japanese architect, it was especially meaningful to contribute an art campus guided by Japanese philosophy and spatial traditions." — Shohei Shigematsu, OMA Partner

The concrete base curves inward to minimise contact with the ground, allowing the native guayacán tree to survive undisturbed beneath the structure. An oculus at the crown of the dome opens to the sky, flooding the cave-like interior with light, while openings around the lower perimeter provide natural ventilation. At the top of the steps, a platform and a portal offer views beyond the natural brush to the ocean.

Shigematsu, who is Japanese, describes the project as especially meaningful in the context of a campus shaped by Japanese philosophy and spatial traditions. What resulted is an incubator of both food and community — a building that serves an agricultural function, celebrates local craft, draws people together, and then slowly, over years, becomes part of the landscape it was built not to disturb.

Key takeaways

• The Mushroom Pavilion's ellipsoidal form was determined entirely by function — optimised for mushroom cultivation and divided into three interior chambers surrounding a central gathering space, with stepped amphitheatre-style shelving holding handmade terracotta pots by local artisans and a panopticon viewing geometry that makes the entire growing process visible from any position inside the dome.
• The concrete shell is burlap-stamped to retain the site's high iron content water, with the explicit design intention that the pavilion will rust and transform in appearance over time — making material impermanence a central architectural principle rather than a maintenance concern.
• The structure's base curves inward to minimise ground contact, preserving the native guayacán tree and the natural landscape beneath the dome, while an oculus, perimeter ventilation openings, and a rooftop platform with ocean views complete a building conceived as both agricultural infrastructure and community gathering space.