The french architect selects two virtuosic compositions of space, light and colour, and a music hall of carefully orchestrated chaos

In-situ concrete makes it possible to create continuous surfaces, leaving virtually no trace of how a building has been assembled. At the António Carlos Siza House in Porto, which Álvaro Siza designed for his brother, it feels almost as though the entire building had been cast in a single pour. The monochromatic yellow finish – which even incorporates the window and door frames – reinforces the impression of a fragmented monolith.

One can imagine how challenging it must be for an architect to design a building for a member of their own family. It is rarely straightforward, and I have heard countless stories. I don’t know the history of this house in detail, nor do I know whether everything went smoothly between Siza and his brother. Beyond that, however, what immediately stands out is the freedom of its organisation.

The plans reveal a fascination with geometry. Lines intersect one another, and there appear to be invisible regulating geometries beneath the composition. There are unexpected spaces throughout; you never quite understand everything at first glance. Certain elements convey stability – the living room plan is almost perfectly symmetrical – yet this order is disrupted by a double-height space, expanding circulation routes, compressed passages and moments where the spaces suddenly open up and breathe.

The views are particularly beautiful. From different points within the house, you can look back out towards other parts. It is almost as though the building is looking at itself. The Casa Gilardi by Luis Barragán in Mexico City is another house in which concrete is used to create highly abstract surfaces. Here, however, the material is rendered rather than left exposed, giving it a texture that captures both light and colour beautifully. The interplay of light in the yellow corridor that leads towards the living room creates a space that feels almost velvety.

There is a remarkable softness, enhanced by the fact that all the walls share the same material character. It is colour alone that transforms them. Unlike the Siza house, the plans could easily have been drawn by a child. On paper, the gallery running alongside the courtyard appears entirely ordinary, yet walking through it is an extraordinary experience. That is the power of architecture: it can create spaces of unimaginable richness from apparently simple drawings.

The tree standing within the courtyard introduces an intensely poetic dimension. One senses that it existed long before the house itself. The architecture has been designed around it, allowing it to become the organising focus of the project – the house is not imposed on nature but adapts to it. This is an idea I’ve explored in some of my own projects, for example the Porto-Vecchio Media Library (2022), where the building was shaped around rock formations and olive trees that we wished to preserve.

Finally, for me, Rem Koolhaas’ Casa da Música is one of the most important buildings of the 21st century because it may well be the first project to establish a complete separation between container and content. Its faceted, monolithic external form – almost like a meteorite resting in the city of Porto – is entirely independent of the interiors. As one approaches the concert halls, the route winds around large volumes, alongside inclined walls, through compressed passages and expanding spaces, generating entirely new spatial tensions.

I take enormous pleasure in seeing this strange object occupying the public realm. Yet there is an equally great pleasure in entering it: discovering the complete freedom of its circulation, wandering through spaces of exceptional scale, and experiencing what feels like a carefully orchestrated form of interior chaos.

Concrete is not usually Koolhaas’ material of choice, but it feels entirely natural. It is difficult to imagine another material expressing the building’s sculptural presence with the same sense of inevitability. 

Dominique Coulon is founder of Dominique Coulon & Associés

Photos Roberto Collovà, Armando Salas Portugal, Barragan Foundation, Hercules Milas, Alamy Stock Photo