What Are Those Grids of Glass in the Sidewalk — And Why Are They Purple?

<p>Listener Britt McEachern is a tour guide in San Francisco, and spends a lot of time walking around city streets. He's noticed grids of glass embedded in the sidewalk and wants to know what they are. Take a journey with reporter Jessica Placzek to learn the purpose and origins of these gems beneath your feet.</p><p><br></p><p>Additional Reading:</p><p>What Are Those Grids of Glass in the Sidewalk — And Why Are They Purple?</p><p>Quiz: Test Your Bay Area Knowledge</p><p><br></p><p>Reported by Jessica Placzek. Bay Curious is made by...