Though the dark, imposing stalagmite in the center of the city is already an eyeful, Cologne has a hefty amount of attractions, ranging from some of the best museums to the best ruins in all of Germany. Explore the Roman world, and visit the current excavation sites in the Archäologische Zone. Wander the halls of the Museum Ludwig or the more understated Kolumba, or be one of the few to make a bee-line for the Museum für Ostasiatische Kunst in the Hiroshima-Nagasaki-Park. Strolling along the city's "green belt" with sunbathing stops in its parks along the way, taking a foot-tour of its Romanesque churches, or digging into the archives at the NS Dokumentationszentrum are also all fine ways to spend a day. Couples shouldn't leave before latching a Love Lock to the Höhenzollernbrücke.