Ypres

Ypres needs 1 day: the In Flanders Fields Museum, dedicated to World War I, and the Menin Gate, with the Last Post ceremony that has sounded every night since 1928 in honor of the fallen soldiers, in a single day. April-September brings the best weather for touring the surrounding military cemeteries. It's inexpensive for Belgium. It was almost completely leveled during World War I, the epicenter of some of its bloodiest battles (including the first use of mustard gas in combat, in 1917), and its historic center, with the imposing Cloth Hall, was rebuilt brick by brick after the war following the original medieval plans.