My three favorite European cities are Tallinn, Krakow, and Vilnius. Like the other two, Vilnius has a picturesque old town that's not too commercial and touristy like Prague, yet isn't sleepy like Toledo. These three are just right--bustling little city-towns that haven't sold out their cultural identities. All three beg you to simply wander the cobblestone streets in an attempt to get lost. Though choosing one is a toss-up in terms of UNESCO criteria and prices, I give a slight edge to Vilnius for its nightlife and its location. In one direction, the insular castle of Trakai is 20 km away, as is the geographic center of Europe in another. Within an overnight train-trip or less, you can reach numerous World Heritage Sites in Lithuania, Poland, Russia, Belarus, Latvia, and Estonia. Another advantage Vilnius holds: it has a strong sense of its various historical periods. The hilltop castle has watched over the city for centuries; the genocide museum remembers the decades watched over by the KGB. Visit the church Napolean wanted to take home with him, or touch the cement blocks that protected democracy-minded Parliamentarians from Soviet tanks on the night thirteen citizens were massacred in 1991. The longer you stay, the more you'll discover.