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Back when I was taking my exams to become a licensed architect the study materials always included a question about thin-shell structures. This is a very specialized type of concrete construction that derives its strength not from the thickness of the material but from its shape. One particularly efficient shape was the hyperbolic parabolid. The strict definition of a hyperbolic paraboloid is, "An infinite surface in three dimensions with hyperbolic and parabolic cross-sections". More simply it's a shape that looks like a saddle.

I always thought it was a joke that the State of Texas thought it was important for architects practicing today to know about thin-shell concrete hyperbolic parabolids because even though they are cool, no one's building them anymore. Constructing the formwork for these complex shapes is incredibly labor intensive and the concrete’s strength can be compromised by small changes in temperature and humidity. Asking a question about them on the ARE exam would be like asking a question about Gothic groin vaults or Victorian mansard roofs.

Pretty much the only person to have had any success building these things was a Mexican engineer by the name of Félix Candela.  I had seen photos of his work in school and although I respected it I frankly never really thought all that much about it beyond that.

Then I got to experience what it was like to be inside a thin-shell concrete hyperbolic parabolid. That made me think about them a lot more.

I happened to attend a wedding at the Chapel Lomas de Cuernavaca, an open-air chapel located about 36 miles south of Mexico City. The wedding Mass was beautiful (even though I didn't understand a word of it as it was sonducted in Spanish)  but it was the chapel that really grabbed my attention. And even though I could appreciate the structural efficiency of the structure's thin-shell I was really blown away by its architectural expressiveness. Even though the structure was only inch-and-a-half thick, it felt like I was enveloped within a cave. But it was a cave that somehow allowed light to penetrate deep inside. It was a cave whose shape directed prevailing breezes through it.

It was a space that was difficult to capture with photographs and that may have been part of the appeal: the architectural experience proved to be difficult to describe. It was a space like no other.

In all likelihood I will never design a thin-shell hyperbolic paraboloid structure. Of course, in all likelihood I’m not going to design a Victorian courthouse or a Gothic cathedral either. But just I am glad courthouses and cathedrals exist, so too am I glad that hyperbolic paraboloids exist.