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.