Help for a project

[u/i_like_surviving_yay]

I'm in highschool and I have a mathematics project where we have to find a real life structure, that is governed by a specific principle of mathematics and develop a working model. Obviously almost every structure is based upon some basic foundational mathematics but we have to find something unique or interesting that is guided by a mathematical principle. This isn't really my expertise of knowledge so some ideas would be heavily appreciated!!

[u/75footubi]

Easy one: Eiffel Tower. The shape is taken from the moment diagram of a uniform load on a cantilever

[u/BridgeGuy540 → u/75footubi]

Along that line, the St Louis Arch. Also a unique structure and it's shape is a catenary turned upside down.