Roman Mars, host of the podcast "99 Percent Invisible," describes some of his favorite examples of clever design from his home turf in Oakland and Berkeley. Then two tour guides from London team up with Rick to recommend an ideal sightseeing week in the British capital. And poet and essayist Lisa Wells shares the insights — and optimism — she gained from interviewing a geographically and ideologically wide range of people battling climate change by improving their own communities.