Alberto Campo Baeza Suspends a Gold Tabernacle Inside a Cube of Daylight in a Madrid Basilica

The Basílica de la Virgen Milagrosa on Calle García de Paredes had been built and later restored, yet it never had a main altarpiece. When the Vincentian fathers approached Alberto Campo Baeza at the end of 2023, the obvious answer would have been to fill the apse with something large: carved, gilded and figurative, in the Spanish tradition of the retablo. Campo Baeza went the other way. He cut a single square opening into the brick apse wall and set a glass cube 1.20 metres on each side inside it, then hung a gold tabernacle at its centre.

The concept comes from the Creed: Lumen de lumine, Light from Light. What interests us is how literally, and how economically, the architect builds that phrase. The altarpiece is less an object than a daylight instrument. Most of the cube pushes outward beyond the apse wall to catch as much natural light as it can, and the tabernacle floats in what Campo Baeza calls a "cloud of light." He claims it is the first time Catholic liturgy has seen a tabernacle suspended this way. Whether or not that holds up, the move is radical in its restraint.

A Point of Light at the End of the Nave

From the entrance, the intervention is almost absurdly small. The long view past the dark pews shows a cross, the pointed vaults, the stained glass and then one glowing square on the central axis. Campo Baeza placed it at eye level for someone walking into the nave, so the cube becomes the vanishing point of the whole church.

That smallness is the argument. A 1.2-metre square cannot compete with ribbed vaults and clustered columns, so it doesn't try. Its brightness does the work instead. In a dim interior, a luminous square reads from fifty metres away in a way that a gilded retablo, with all its shadows and ornament, often fails to.

Six Steps Up to the Tabernacle

Raising the tabernacle meant reworking the floor. A flight of six pale stone steps now climbs from the altar zone toward the niche, so the priest can reach it. The symmetrical view shows how much the stair contributes: it turns a hole in a wall into a destination and gives the composition a base, much as a plinth does for a sculpture.

The architect also kept the circumvallation, the walkway that loops behind the apse. That is a quiet act of respect. The church's original circulation stays intact, and the new work occupies only the axis and the wall.

Gold Suspended in a Cloud

Up close, the device reveals its logic. White translucent glass diffuses the daylight evenly, so the cube glows without any visible source and without the hot spots of clear glazing. Against that field, the gold tabernacle seems to hover. The silhouetted visitor in front of it shows how the cube acts as a backlight: the figure goes dark and the object goes bright.

The precision here is real, not rhetorical. The panes were levelled with laser beams and joined with ultraviolet-cured bonding, which removes mullions and visible frames from the cube's edges. Any mechanical joint would have broken the illusion of a weightless volume of light. Lighting consultants from Ferram, Signify and iGuzzini supported the work, presumably for the hours when daylight runs out, but the design clearly treats electric light as backup rather than the main act.

Testing the Idea in Models

The sheet of eighteen study model views is revealing. Each one varies the proportion of the niche, the steps and the gold square, and each has a standing figure for scale. You can see the team calibrating how small the square could get before it lost presence, and how tall the stair should be relative to a person.

Set beside the finished axial photograph, the models show how little changed in spirit and how much was refined in measure. This is Campo Baeza's method in miniature: pick one idea, then spend the effort on dimensions instead of adding elements.

Plans and Drawings

The site plan places the basilica in a dense block of central Madrid, and the church plan maps the rib vault pattern, the apse and the entrance towers between two streets. Against that scale, the altarpiece is almost a single point.

The chancel plan and the axonometric clarify the relationship between the central stair, the clustered columns and the box set into the wall. The axonometric is especially useful because it shows the cube as a framed opening, not as an applied object.

The interior elevations and the perspective down the aisle confirm the hierarchy of cross, cube and stepped altar on one vertical line, with human figures giving the 1.20-metre cube its true scale.

The sections are the most telling drawings. They show the box cutting through the apse wall and pushing out beyond it, next to the adjoining parish house. The 1:3 edge details record the glass joints that make the cube read as a seamless volume.

Why This Project Matters

Contemporary church interventions often swing between two failures: timid pastiche or loud contemporary objects that fight the existing building. La Milagrosa avoids both. It adds almost nothing physically, takes nothing away from the historic interior, and still gives the basilica the focal point it lacked. The budget of material is tiny; the budget of thought is not.

For architects, the lesson goes beyond sacred space. Daylight is treated here as the primary building material, and structure, glass and detailing all serve its delivery. A square opening, a translucent cube and a suspended piece of gold make a convincing case that meaning in architecture can come from precision and light rather than accumulation.

La Milagrosa Altarpiece by Alberto Campo Baeza, Madrid, Spain, 2024. Photography by Javier Callejas Sevilla.

About the Studio

Share Your Own Work on uni.xyz

If projects like this are the kind of work you want to make, uni.xyz is a place to publish your own, find collaborators, and enter design competitions.