13 days in Europe: London, Barcelona, Florence, and Paris

In less than two weeks, I'll be touching down at Heathrow, ready for 13 days of European adventures. Whoa. In an effort to not completely exhaust myself (and Steve), I've pulled some must-see places and recommended restaurants, but I'm not doing a full-out itinerary. (I'm using Stay.com to keep track of everything, which allows you …