In Bologna, the former convent of San Michele in Bosco contains a 162-meter hallway that’s “aimed” at the Asinelli tower 1,407 meters from the window. This produces an odd effect: As you move north along the hallway toward the window, you’re approaching the tower, yet it seems to shrink. This is because the retinal size of the window’s aperture increases enormously as you approach it, while the retinal size of the distant tower remains relatively unchanged.

Similarly, as you back away from the window the tower seems to grow and draw closer, because the “shrinking” window shuts out the panorama, leaving only the tower in view. The illusion was first reported on a 1714 map by Paolo Battista Baldi of the University of Bologna.

The city contains a second “vista paradox” in the hermitage of Ronzano, where another long hallway is oriented toward the Sanctuary of San Luca 1,970 meters away. The Sanctuary seems to shrink as one approaches the frame and to grow as one retreats.