We love—and fall in love in—cities that engender the main elements of smart, sustainable urbanism.
Kaid Benfield, Sustainable Cities and Smart Growth Director for the NRDC, answers this question in his annual Valentine's Day must-read post on the intersection of smart, sustainable urbanism, livable streets, and romance:
Prague. Venice. Rome. Paris. These are some destinations that perennially make "ten-most-romantic cities” lists. I just looked at three such sites, and all four cities were consensus picks. Vienna and Lisbon each made two of the lists.