The Gateway to the West
The St. Louis Gateway Arch is shaped as an inverted catenary. A catenary is the shape that a chain takes on while being held by the two ends. Christiaan Huygens, a Dutch mathematician, named this curve from the Latin word catenarius, which means “related to a chain.”
Equation for catenary curve: y = k cosh(x/k), a hyperbolic cosine curve, of course.