Detail, roof of portico; zinc roofing added 2000-2002; The chapel for the Colonia Güell, a settlement for Güell textile workers at Santa Coloma de Cervelló, near Barcelona, was commissioned in 1898. Its form was derived from a unique catenary modeling system, which Gaudi invented using wires, canvas, threads and hanging weights to simulate the structural stresses. The interior is created from highly complex ribbed vaults of stone, brick and tile in squat, quasi-parabolic shapes carried on inclined columns of roughly chiseled stone and textured brick. Outside, inclined rubble walls and columns grow out of the ground like trees, with teardrop-shaped windows between their roots. The whole building expressed Gaudí’s aim to achieve an organic un...