For Mr. Santos, math can also inspire ideas about structures that have already been built — a new way to see and appreciate the world. Inspired by this idea, The New York Times created a virtual tour ...

Once a century, a very special day comes along. That day is today — 9/16/25. Pi Day (3/14) often comes with sweet treats; Square Root Day (4/4/16 or 5/5/25, for example) has a certain numerical rhyme.