A pair of tour guides from Greece tell us how the island of Crete offers a natural experience unlike any other. Then travel writer Mark Adams describes his 3,000-mile voyage along the coasts of Alaska to follow what the Harriman Expedition saw in 1899. And a Dutch biologist explains how urban evolution is happening faster than we used to think all over the world.

• Anastasia Gaitanou, Greek tour guide and historian
• David Willett, tour guide and expert on ancient Greece
• Mark Adams, author of "Tip of the Iceberg" (Dutton)
• Biologist Menno Schilthuizen, author of "Darwin Comes to Town" (Picador)

• The impressive Minoan Palace of Knossos is about a half hour's drive from the Crete capital city Heraklion.  
• Rick writes about visiting the Gorge of Samaria on Crete.
• David Willett can be reached about his custom guiding through LinkedIn.
• Anastasia Gaitanou leads tours of Greece from her home base in Thessaloniki.
• Mark Adams describes his 3,000 mile journey on the Alaska State Ferry system, to retrace the route of the 1899 Harriman Expedition, in his book "Tip of the Iceberg."
• Mark Adams discusses the challenges of hiking to Machu Picchu on Travel with Rick Steves program #480, and his search for evidence of the legendary lost city of Atlantis on program #501.
• Biologist Menno Schilthuizen is the author of "Darwin Comes to Town."
• Menno also leads eco-tourist adventures in which "citizen scientists" discover and name new wildlife species in the jungles of Borneo.