Gaudí Beyond the Sagrada Família
Gaudí is routinely filed under whimsy. The buildings look organic, so the assumption is that they were designed intuitively. They were not — they were engineered, often by methods that were ahead of their time.
The hanging chain model
For the Colònia Güell crypt he built an upside-down model out of strings weighted with small bags of birdshot. A hanging chain under its own weight forms a catenary — the shape that carries pure tension with no bending. Invert that shape and it becomes a structure in pure compression, which is exactly what masonry is good at.
He photographed the model, turned the photographs over, and drew on them. This is form-finding: letting physics generate the geometry rather than imposing a geometry and then propping it up. It took computational analysis decades to catch up with what a string model had already solved.
Ruled surfaces
The complex curves in his later work — hyperbolic paraboloids, hyperboloids, helicoids — are ruled surfaces, meaning every point lies on a straight line. That has a practical consequence: they can be built with straight timber formwork and cut by straight-edged tools, which is what made those shapes buildable in stone and brick at all.
The buildings to see
Casa Batlló for the way light is graded down a courtyard using progressively darker tiles so the lowest floor receives as much light as the top. Casa Milà for a stone façade with no load-bearing walls, the floors carried on columns and beams, which is why the interior partitions can move. Park Güell for the retaining structures, where the inclined columns follow the line of thrust. Colònia Güell for the crypt that proved the method.
The unfinished argument
The Sagrada Família continues under construction from surviving models, drawings and a great deal of interpretation, since much of the original material was destroyed in 1936. Whether the result is Gaudí’s building or a reconstruction of an idea of it is a live and genuinely unresolved argument among architectural historians.