"It may have taken 300 years—plus the unification of two churches—to build St. Stephen’s Cathedral in Metz, but the Gothic masterpiece is one of Europe’s tallest churches (at 140 feet) and boasts more stained glass than any other cathedral in the world (70,000 square feet, to be exact). In fact, St. Stephen’s has so much stained glass that it was nicknamed La Lanterne du Bon Dieu , or God’s Lantern. When visiting (entry is free), look for the windows by famed artists Jacques Villon and Marc Chagall. Afterward, walk a few steps to Place d’Armes in the Old Town, where outdoor cafés and restaurants abound and, during Christmas, a market takes over the arcade."