Before we went to Barcelona, it was relatively easy for me to describe the Sagrada Famila. "It's this cathedral, designed by Gaudí, and it's pretty wild on the outside. They started building it in the late 1800s and construction isn't finished yet."
Now, though, having been... it's hard for me to articulate my reaction. Astonishment. Awe. Infatuation. I wanted to move in and never leave. I wanted to photograph the light in there forever.
I'll say this: Although most of what people talk about is the exterior, and how wild it looks, it was the interior that really enthralled me. Gaudí was a man in love with light and how it moved and changed. The stained glass is matched to the facets of every surface in the building, so as the sun moves, it's almost as though the shape of the interior is changing. I found the entire experience, well, astonishing.
for mah nerds
One of the things that delighted me about the experience was how Gaudí used math and engineering in service of his vision. Check out this diagram from the exhibition in the basement, showing how in different parts of the building he used proportional sections of ellipsoids to create the shapes the light is playing off of.
He also used an elaborate system of strings and weights to design the catenary arches the building is constructed with. I didn't get a picture of his system, but the Memetician has a great explanation of Gaudí's work with strings and tension.