March 14th is annually known as Pi Day since the numerical date replicates the first three digits of pi. Every year, the Exploratorium opens its doors to the public for free on Pi Day, one of only a few rare annual free admission days. Come down to Pier 15 to celebrate the mathematical holiday by exploring the museum’s many interactive art, science, and human perception exhibits. The Exploratorium will be hosting a series of fun pi-themed activities, and also serving visitors plenty of pie. Adults and children alike will have a blast at this playful and educational museum, a San Francisco staple.