Leo Villareal is an artist, but his tools aren't paint and canvas; he manipulates light, color and computer code to create monumental works of public art. In a dazzling talk, he takes us inside his efforts to light up some of the world's most iconic bridges — including an installation of 25,000 LED lights on San Francisco's Bay Bridge and a piece uniting nine bridges along London's River Thames — and shows how public art can transform a city.