Strasbourg

Strasbourg's old center sits on an island ringed by the Ill river, and that Grande Île has been on UNESCO's World Heritage list since 1988, so the best of the city is one easy loop. The Gothic cathedral and its astronomical clock fill a morning, the half-timbered lanes of Petite France fill the afternoon, and the winstubs serve Alsatian food and wine in the evening. December brings one of Europe's best-known Christmas markets and the crowds that go with it; spring or fall is the calmer choice for a slow weekend.