We’ve always been more into the Blackberry (tactile buttons = email ease), but a visionary new iPhone application designed by husband-and-wife architecture team Cheng + Snyder is making us question everything. Namely, where the Buckminster Fuller dome would have been located and why that Battery Park airport failed to materialize. Thanks to the pair’s clever, transformative Museum of the Phantom City tool, Apple phone users can scout over 50 unbuilt architectural sites around the city with a feature that describes each proposed project through the architect’s own notes.

Screenshots from the Museum of the Phantom City application for iPhone.

The virtual map guides users around Manhattan to sites where projects of sublime scale — much more form than function — were planned but never built. A.G. Sulberger of the New York Times spoke to Irene Cheng and Brett Snyder about their brainchild. Cheng points out that although New York is “the city that never was but could have been, sort of an alternate future,” these types of visionary proposals are not always destined for the back burner. To cite a few current examples: the Empire State Building, Central Park (“an immense swath of artificial nature in the heart of the city”) and, most recently, the High Line (“the transformation of a hulking piece of urban detritus into a magnetic public space”).

The interactive website launches with a citywide scavenger hunt this Saturday, October 3. Meet at the base of the aerial tram station that goes to Roosevelt Island at 1 p.m., iPhone in hand.