It seems that every city has its own version of pop-up parks, parklets, better blocks and other temporary design interventions intended to add life and fun to city streets. Cathy Ho curated a celebration of these clever urban actions in a major exhibition, 'Spontaneous Interventions: Design Actions for the Common Good.' It first appeared as the official U.S. presentation at the 13th International Architecture Exhibition at the Venice Biennale in 2012, and it continues to tour the U.S., first in Chicago and most recently in New York. This week we talk to Cathy Ho on 'Knight Cities' about how the pop-up movement started, what is fueling its growth and how it is changing cities. You can follow us on Twitter at #knightcities or @knightfdn. And if you have ideas for people you'd like to hear more from, please email me: Coletta (at) knightfoundation.org.