Rick marks 20 years of his radio show by revisiting some memorable guests and what they've taught us about travel. Then author Paul Theroux celebrates his 84th birthday as he contemplates the passage of time in his new short-story collection, "The Vanishing Point." And actor Martin Sheen describes how his experiences filming overseas have come to influence his political activism.

For more information on Travel with Rick Steves - including episode descriptions, program archives and related details - visit www.ricksteves.com.