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.

Two German tour guides let us in on the back story behind Berlin's most memorable monuments to their country's turbulent history. Then two Turks tuck into a discussion of the traditional Turkish street eats, comfort foods, and desserts they recommend for a tasty visit to Istanbul. And an American who met — then married — a local artist in Bhutan shares tips for surmounting the logistical hurdles of visiting this remote Himalayan kingdom.