iPhones and mobile devices have changed the way we navigate the city. Apps like Google Maps and Yelp put an unprecedented amount of information about the city at one’s fingertips.

Mobile apps are mostly used to locate nearby restaurants and restrooms. Two architectural designers have built a new app that uses GPS technology to explore "how mobile media can deepen and intensify urban experience, perhaps even introducing new pleasures and mysteries of the metropolitan condition."

The app is called “Museum of the Phantom City,” and it turns the iPhone into an "architectural dousing rod." As you wander the streets of New York, it shows a city that could have been — 50 architecture sites that never got built.

WNYC’s Soterios Johnson took the iPhone tour with Irene Cheng, one of the co-creators of the app. They started off at Bryant Park, the site of a proposed airport. Take a listen to the tour.

Cheng and her partner Brett Snyder developed the App with the help of the Van Allen Institute. The beta version of the app is available for free on iTunes, and you can see the whole tour on their website. Our partner Urban Omnibus has a feature up right now on the project.