Triple-spiral staircase of Bonaval Curiosity · Santiago de Compostela, Santiago, A Coruña Image of Santiago de Compostela, not of the place itself. A tour de force by Domingo de Andrade in the convent of San Domingos: three independent helices, with single-piece steps held by an outer rib, that climb without ever crossing, and of which only one reaches the viewing gallery. Photo: Diego Delso (CC BY-SA 4.0) What to see and do in Santiago de Compostela