A Building Egress Feature that Creates an Optical Illusion

With a capacity of over 80,000, Milan's San Siro is Italy's largest stadium. Originally built in the 1920s, it was renovated multiple times during the 20th century. Its most significant overhaul was in the late '80s, in preparation for Italy's hosting of the 1990 World Cup. Architects Giancarlo Ragazzi and Enrico Hoffer, along with engineer Leo Finzi, added eleven reinforced concrete towers containing helical walkways to provide access to the stands.Image: Arne Müseler, CC BY-SA 3.0 Image: Prelvini, CC BY-SA 4.0 While the structure does contain elevators for the mobility-impaired, Italians—like Europeans in general, and in contrast to Americans—generally have no issue with taking the walkway, rather than queuing for lifts. And whether the architects intended it or not, there is a nifty optical illusion that takes place after a match has let out. As fans descend the walkways, it appears as if the towers themselves are rotating:Video: Dorian PellumbiWhile the 1990 World Cup was a long time ago, San Siro will once again take its place on the world stage: It will host the opening ceremony of the 2026 Winter Olympics.

May 9, 2025 - 15:30

A Building Egress Feature that Creates an Optical Illusion

With a capacity of over 80,000, Milan's San Siro is Italy's largest stadium.

Originally built in the 1920s, it was renovated multiple times during the 20th century. Its most significant overhaul was in the late '80s, in preparation for Italy's hosting of the 1990 World Cup. Architects Giancarlo Ragazzi and Enrico Hoffer, along with engineer Leo Finzi, added eleven reinforced concrete towers containing helical walkways to provide access to the stands.

Image: Arne Müseler, CC BY-SA 3.0

Image: Prelvini, CC BY-SA 4.0

While the structure does contain elevators for the mobility-impaired, Italians—like Europeans in general, and in contrast to Americans—generally have no issue with taking the walkway, rather than queuing for lifts. And whether the architects intended it or not, there is a nifty optical illusion that takes place after a match has let out. As fans descend the walkways, it appears as if the towers themselves are rotating:

Video: Dorian Pellumbi

While the 1990 World Cup was a long time ago, San Siro will once again take its place on the world stage: It will host the opening ceremony of the 2026 Winter Olympics.