For fifteen years, three architects--James Cathcart, Frank Fantauzzi, and Terence van Elslander--from three different cities have held an ongoing collaboration, creating installations and other works of innovation and art about the act of building. Pamphlet Architecture 25: Gravity catalogs a cross section of their many works, from the portable toilets installed in the facade of New York's StoreFront for Art and Architecture to "Big Orbits," a giant solid and a giant void constructed from 4600 shipping palettes. Although strongly conceptual, their work reminds us that a primary function of architecture is to engage the public.