Piers gough

Thin shells give me a kind of surreal thrill. Between the wars, when this type of construction was at its height, ultra-thinness became an engineering obsession. Architecturally, thicker shells would, no doubt, have been fine enough. But these engineers were pushing structural concrete to its exquisite limit.

The Zarzuela Hippodrome in Madrid has always inspired me. The engineer, Eduardo Torroja, pushed the feasibility of the shell to the limit, using an asymmetrical section to balance out the weight. It’s unbelievably thin and delicate – the roof edge is just 60mm. It looks like it’s fluttering in the wind.

The Spanish-Mexican architect and engineer Felix Candela was perhaps the master of the thin shell. The Oceanografic aquarium and restaurant in Valencia, which was his final work, is almost ethereal – a delicious ruffle of paper-thin concrete. The opposite of brutalism. Quite often, these shells are slightly spoiled when the facade is filled in, by the weight of the glazing bars. But here, the glazing is very slight, so a sense of lightness pervades the building.

My final choice is a fabulous use of concrete in its rawest state: Lina Bo Bardi’s SESC Pompéia, a sort of leisure centre for the São Paulo shop workers’ union. The scheme is dominated by two very industrial- looking concrete towers with windows that look like they’ve been punched out by a fist. One contains a pool and gym spaces, all on top of each other, and the other houses changing rooms.

The reason for the vertical stacking is interesting. When Bo Bardi got the job, she found that people were already occupying the old industrial buildings on the site, making things and generally having a great social time. So she decided to keep and refurbish them – leaving less space for the new buildings.

The existing structures, which date from the 1920s, show a different use of concrete again. Where the towers are awe-inspiringly raw, the factories are sharp and precise. They use the Hennebique system – the first system-built reinforced concrete frame, which was actually imported from Britain. Rather than having separate columns and beams, the portal frame acts as a monolithic structure, which saves on material. It’s also quite elaborate, with almost decorative openings like a Vierendeel truss.

Bo Bardi was very imaginative with this space, cutting a wavy pool that runs like a river through the concrete paving. There’s also a sort of seaside boardwalk, where people just hang out and sunbathe. It’s a wonderful reinvention.

Piers Gough is a director of CZWG Architects

Photos Ana Amado, Carlos Dominique, Alamy Stock Photo