Philadelphia’s beloved experimental theater group Pig Iron offers this walking tour, called Franklin's Secret City. This adventure game and immersive, audio experience is an iPhone app for two players, ages 10 and up.

Co-writers Dan Rothenberg (Pig Iron’s Co-Artistic Director) and Robert Quillen Camp (who co-wrote Pig Iron’s Pay Up and the OBIE-winning Chekhov Lizardbrain) invented an alternate universe of secret societies, hidden technologies, and inventions that border on magic, all hidden within Philadelphia’s historical sites and artifacts. 

In Franklin's Secret City (FSC), participants are the latest recruits to the New Promethean Society, a secret group of inventors and polymaths, created to protect some of Benjamin Franklin’s more dangerous discoveries. This family-friendly adventure features a series of mind-bending puzzles that must be solved as a duo while exploring the exterior of the American Philosophical Society and Signer’s Garden, near 5th and Chestnut Streets in Philadelphia. 

The app is available (on iPhones only) in “open-beta” as it is still a work in progress. For the moment, both players must use iPhones, since the app isn't available on Android devices.

Open-beta testing is from June 8-September 22, 2021 during daylight hours beginning at Signer’s Garden, southeast corner of 5th and Chestnut Streets. The experience takes about 45-60 minutes and requires headphones. The entire experience is free, but donations to Pig Iron are encouraged.