It is one of the most fascinating mysteries of Bologna, as well as one of the most photographed views of citizens and tourists: the Asinelli tower seen from the window of the monumental corridor of the monastic complex of San Michele in Bosco.
From this vantage point, one of the most beautiful in the city, you’ll come across a unique optical effect.
It is called “telescope effect”. This can be experienced by looking at the Asinelli tower, symbol of the city of Bologna, from the long corridor on the first floor of the monastery of San Michele in Bosco, now Rizzoli hospital.
Moving along the corridor that “points” to the tower (at 1,407 meters away) the image of the tower is enlarged the more it is distant. Going through the corridor, therefore approaching the window facing north from which you can see the tower, it becomes smaller.
A study conducted by the Department of Psychology of the University of Bologna – published in the scientific journal Perception – explained that this perceptual illusion occurs when a distant object is observed through an opening like a window. When one moves away or approaches the window, the latter undergoes strong modifications in the retinal projection, while the framed object, being far away, remains substantially unchanged in dimensions.