Europe is overwhelming in the best possible way. One minute you’re standing in front of a cathedral that was built before the United States existed, and the next you’re eating the best pastry of your life on a quiet street you didn’t even mean to find. Europe is castles and coastlines, museums and mountains, tiny towns that look like storybooks and big cities that never stop moving. And if you’re trying to plan a trip—especially your first—this is the moment where most people get stuck. Because “the best places to visit in Europe” is a big question. The truth...