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.

Europe brims with world-class art, and we contemplate some of the continent's truly outstanding paintings, sculptures, and historic edifices. Then we learn about the historic and ecological importance of the Gulf of Mexico from a professor in neighboring Florida. And we consider the humble guidebook and what its pages can tell us, both in the moment and long after the trip is done.

A tour guide from Greece delves into the importance of food, family, and traditions in his homeland. Then a Francophile offers advice on how to take on the vast collection of the world's largest — and arguably greatest — museum. And guidebook researcher Cameron Hewitt shares discoveries from his travels in the Balkans, an affordable and rewarding alternative to the tourist crowds of western Europe.

Two countrymen explore Ireland's reverence for their national poet, W. B. Yeats. Then a Dublin journalist shares what it was like to grow up amid the turbulent societal changes in his city during the 1960s and '70s. And a guide from Belfast tells us why an Emerald Isle itinerary should include a visit to Northern Ireland.

Delve into the remote outposts and refuges across the globe where travelers have stopped along the course of their adventures. Then hear about the highest views in Wales — and how to reach them — and learn about the country's slate mining heritage. And from Alps to caves, vineyards to beehives, catch the buzz of the natural wonders on display in Slovenia.

Look at what's behind Carnival and Mardi Gras celebrations around the world by learning about the festive season's origins and customs in Germany's Rhineland. Then hear what's been added to the World Monuments Fund's latest "watch list" of endangered cultural sites around the world. And get recommendations for must-see experiences in Alaska, along with tips for planning adventures across the Last Frontier.

Two English tour guides explain what Brits mean by a "rough and ready" pub and how to find some of the UK's best pub grub. Then a father-and-son tour-guiding duo invite us to fall in love with their favorite corner of France. And BBC journalist Eliot Stein shares insights from his travels in search of the world's oldest disappearing traditions, giving us a peek into what it's like to be the last to carry a cultural torch.

Listen in as an artist who helped restore Monet's gardens explains why the French painter first created these colorful gardens at his house outside Paris. Then hear how renovating a house on an island off the coast of Brittany can feed your wild side. And find out what happens when you marry an Italian…and your new in-laws live next door. Plus, an adventure cyclist shares the story of a timely romantic surprise that came when he needed it most.

This week we explore three of the most charming — and most popular — of Europe's Old World cities: Two tour guides get cheeky as they make the case for which of their own hometowns — Prague or Budapest — offer the best experiences for visitors with limited time in central Europe. And expert locals catch us up on changes afoot in Lisbon, offering strategies for navigating its more crowded sights so that you can still enjoy an authentic taste of today's Portugal.

We hear why the city of Potsdam — home to elegant Prussian palaces and parklands, all in quick reach of central Berlin — is worth a day's visit. Then we get a sense of what life was really like for the emperors of ancient Rome, with the help of classicist Mary Beard. And we travel back to 1978 with Rick and his longtime buddy Gene Openshaw as they retrace their post-college adventures along the infamous "Hippie Trail" from Istanbul to Afghanistan to India, all the way to Kathmandu.