At Columbia University, New York, I saw these tiles in St.Pauls Chapel. The chapel was completed in 1907. The staircase is constructed from three courses of these slender tiles and they are absolutely beautiful. They are by Rafael Guastavino and they collectively work as structural tiles. Guastavino was a Spanish immigrant to the US in 1881 and brought with him the Catalan technique of timbrel vaulting.