Over the next two weeks, Next City will unroll short profiles of 77 people, places and ideas that have changed cities this year. Together, they make up our 2012 Disruption Index. Forefront subscribers can download the Index in full as a PDF, complete with beautiful designs and graphics by Danni Sinisi. Readers who make a $75 donation to Next City will have a full-color printed copy of the Index mailed to them.

The Occupy movement brought many issues to the world’s political consciousness. In New York, one of the unexpected revelations was the rediscovery of the odd case of privately owned public spaces. Zuccotti Park, the adopted home of New York’s Occupy Wall Street encampment, is not actually a park in the traditional sense. Rather, it’s a private plaza created as a sort of tradeoff between city zoning officials and real estate developers that allows a building to grow taller in exchange for some publicly accessible space on the ground.

These spaces have been around since the 1960s, and no one knows them better than Jerold Kayden, a professor of urban planning and design at Harvard. His 2000 guidebook to all the privately owned public spaces in New York has garnered new attention, as urbanists and city officials try to understand just how public-but-not-public places fit into the urban realm. And now, Kayden has started a group to pay even closer attention to these spaces: Advocates for Privately Owned Public Spaces is aiming to create a set of guidelines to try to revitalize these underutilized spaces and make them better and more accessible in New York and other cities. Kayden’s long-held expertise is finally being recognized.

Nate Berg is a writer and journalist covering cities, architecture and urban planning. Nate’s work has been published in a wide variety of publications, including the New York Times, NPR, Wired, Metropolis, Fast Company, Dwell, Architect, the Christian Science Monitor, LA Weekly and many others. He is a former staff writer at The Atlantic Cities and was previously an assistant editor at Planetizen.