Gaudi shunned flying buttresses yet still needed to ensure that his buildings stayed up, so catenary arches were the solution. On a tour of La Pedrera I came across a brilliant depiction of how to visualise them as hanging chains:
and then, in a mirror, to see how they could form self-supporting domes:
It was appropriate that these models were in the attic (which was originally used for washing and drying laundry) of the La Pedrera apartment block, because 270 catenary arches support the undulating roof. There was a fascinating model of the attic, which to my mind looked like nothing so much as an old-fashioned carousel for holding slides. I guess you need an awful lot of catenary arches to replace a handful of flying buttresses.
To reinforce Gaudi’s focus on organic forms in his architecture and design, the exhibition also contained the skeleton of a python: