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The Convent of Santo Domingo de Bonaval, in Santiago de Compostela, has a triple helical staircase that, in a bold and revolutionary layout, unique in the world, shares the same cylinder, each of them connecting the corner of the cloister with a floor different from the convent building.

This prodigy of architecture, but also of mathematics, physics, geometry and, of course, of baroque art, is made up of a series of steps, each one made of a piece of granite weighing about 200 kg.

They are slightly recessed into the wall and subtly connected to the lower step through an exterior rib, leaving a small horizontal gap between them through which light passes.

Assembled step by step, with hardly any scaffolding or supports, the thickness of the steps is so small that the structure seems to float in the air, as seen in La Vanguardia’s Readers’ Photos.

The views from below or from above are different, but in both cases that perfect helix and its diaphanous clarity amazes. For the first 150 years it did not have a railing, which should have accentuated these impressions.

The author, Domingo Antonio de Andrade (1639-1712), came from his native Cee, near Finisterre, on the Costa de la Muerte and filled Santiago with life and baroque art. He began as a carver of images and altarpieces, becoming one of the most important architects in Galicia, he worked on the cathedrals of Lugo and Ourense and left beautiful civil constructions or superb works in Compostela, such as the Clock Tower, which we popularly call Berenguela, transferring to the tower the beauty that the empress of that name, buried in the cathedral, had: the daughter of Ramón Berenguer III, count of Barcelona and wife of Alfonso VII of León and Castile.

This woman, who died at the age of 33 in the 12th century, made such an impression that it is still said here, of a woman or a tower: “She is as pretty as a Berenguela.” Or maybe it was only like that because she was commissioned by a bishop named Berenguel of Landoria… so long ago… Who knows?…

Returning to the spiral staircase, I will tell you that it is located right next to the Museo do Pobo Galego and the Pantheon of Illustrious Galicians, but these are stories for another day.