New York, NY —

A heliport on top of Bryant Park? that's just one of New York City "ideas" that were never built. But now you can take a self-guided tour of them, with the help of a new iPhone application called "Museum of the Phantom City".

It uses the same GPS technology that apps like Yelp use, but instead of showing you where the nearest bathroom or Korean restaurant is, this app shows you visionary and sometimes bizarre city structures that never made it off the drawing board. Architect Irene Cheng co-designed the app, and I met up with her in Bryant Park the other day, to check it out.

To learn more about this iPhone app, see images of some of the visionary sites we talked about, and sign up for our Halloween Day "meet up" when Irene Cheng and her partner will take a group of WNYC listeners on a guided tour (no I-phone needed), Check out the culture page .