The Truffle — A Cave Built by a Cow

The most interesting buildings are often built the wrong way. Anton García-Abril of Madrid-based Ensamble Studio didn’t use steel formwork, curtain wall systems, or even rebar to build his guest cabin on Spain’s northwestern coast. He used hay bales, pump-truck concrete, and a hungry calf named Paulina.

The project is called La Trufa — The Truffle — and it sits on the Costa da Morte, the aptly named “Coast of Death,” a stretch of Galician coastline littered with centuries of shipwrecks and mossy boulders. From the outside, the structure blends almost imperceptibly into the landscape. It looks like just another stone pulled from the earth. That’s entirely the point.

The Construction Method

The process reads more like a geological event than a building sequence. García-Abril’s team dug a pit in the hillside, then piled the excavated soil around its perimeter — not as decorative landscaping, but as the actual formwork. No lumber, no plywood, no prefabricated systems. The retained earth became the mold.

Inside the pit, the crew stacked hay bales to define the interior volume. Concrete was then pumped in around and over the bales, flooding the cavity between the earthen walls and the compressed hay. No rebar. The mass concrete, unreinforced, was left to cure against the soil and around its vegetable core.

When the concrete hardened, the earth was stripped away to reveal what García-Abril describes as “an amorphous mass” — a boulder. Not yet architecture. Just a stone. The ground had imprinted itself into the surface, lending the exterior its texture, color, and form. The earth gave; concrete received.

Quarry machinery was then brought in to make surgical cuts — slicing open the mass to expose what was inside: hay bales compressed and twisted by the hydrostatic pressure of the surrounding concrete. The material had been crushed but not consumed. That job fell to Paulina.

The calf was allowed inside to eat her way through 50 cubic meters of hay over the course of a year, gradually hollowing out the interior until she left as a fully grown 300-kilogram heifer. Space appeared, as García-Abril put it, “for the first time.” The architecture had been carved by an animal.

The Interior: Cave Logic Meets Modern Precision

What Paulina left behind is something no conventional forming system could have produced. The stacked bales imprinted a horizontal rustication into the walls, while the ceiling developed gentle stalactite-like forms where wet concrete slowly seeped down into the hay. The texture is primal — rough, layered, geological — the kind of surface that takes decades to achieve through weathering and here arrived in a single pour.

This is where the project connects to something deeper than clever construction. The cave has always been architecture’s origin point — shelter carved from the earth, space defined by compression and darkness rather than frame and enclosure. The Truffle isn’t nostalgic about that. It doesn’t romanticize the primitive. It simply takes the logic seriously, then resolves it with a single decisive modernist move.

A large square window was cut into the wall facing the Atlantic Ocean. One enters from the opposite side, stepping down into the space, before the dramatic vista unfolds. The window doesn’t apologize for being modern. It doesn’t try to blend in with the cave texture. It frames the horizon like a painting — a single taut line of blue against all that compressed, irregular mass. The contrast between the rough interior and the crisp steel-framed opening is the whole argument of the building, stated in one gesture.

A small skylight was also cut into the ceiling, capping the aperture to bring light down into the cave from above. Interior finishes are minimal — cement-bonded particleboard for floors and shelving, smooth surfaces that acknowledge the roughness around them without competing with it.

Scale and Economy

The finished space is just 25 square meters — roughly 270 square feet. García-Abril referenced Le Corbusier’s Cabanon, the famously spare seaside cabin in the South of France, as the program model. The comparison is instructive: both projects compress the essentials of habitation into a single room with a commanding view, stripping away everything unnecessary. But where Corbu’s Cabanon is built of warm timber and carefully composed joinery, the Truffle’s interior is monolithic, geological, indifferent to human scale in the best way.

The construction cost was kept remarkably low. The “formwork” was soil. The interior finishing was outsourced to livestock. The structural system was unreinforced mass concrete — one of the oldest building materials in continuous use. What García-Abril spent was time, patience, and a willingness to let the process be part of the design.

Why This Matters

From a professional standpoint, the Truffle is a useful reminder of what’s possible when the architect is willing to work outside conventional building logic. The construction industry has a very narrow definition of efficiency — speed, standardization, tolerance management. What García-Abril demonstrated is that there are other efficiencies available: the efficiency of using the site itself as formwork, of using biological processes instead of mechanical ones, of letting material behavior drive formal outcome rather than suppressing it.

The result is a building with genuine material character — not because expensive finishes were applied, but because the construction method inscribed its own record directly into the surfaces. Every ridge on the wall is a hay bale. Every drip on the ceiling is a moment of concrete in motion. The building is its own construction document.

That’s a quality almost impossible to achieve through conventional means, regardless of budget. And it was done here with hay, a pump truck, and one well-fed cow.

Project: La Trufa (The Truffle)

Architect: Antón García-Abril / Ensamble Studio

Location: Costa da Morte, Galicia, Spain

Built Area: 25 m²

Completion: 2010

Photography: Roland Halbe

Referenced Link:
Dezeen - Trufa by Anton Garcia-Abril

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