Follow Maisy! It's one way to see a city: pick a subway line, any line, and ride to the end. In theory, whatever narrow perceptions you've acquired by sauntering through any metropolis' most busy downtown streets will be balanced out by impressions of its flavor of ragged urban edge. That's precisely what my friend Tanveer and I did when we were trying to think, a few years ago, of a creative way to explore Lisbon. Miles out from the tightly gridded 18th century streets of Baixa, the Portuguese capital's heart, a sprawling housing estate greets anyone arriving at the end of the line with splashes of bold color -- and creepily empty streets. It was exactly the contrast with the Lisbon depicted on postcards and tour guides I that would have imagined. Most termini, though, aren't very representative of the city's outer rim. The end of the line is also a starting point -- a place where many begin their journeys on cities' rapid transit systems after disembarking from buses and cars. That means they're often hubs of activity that mirror the bustle of urban cores -- with the crucial distinction that they're rarely as well-known or experienced by anyone who doesn't live nearby, as foreign to most residents of those cities as to travelers. In Berlin, I lived in a bizarre neighborhood of vast, snaking concrete buildings a long walk from the final stop on the U6 line. At Alt-Mariendorf, the line's last station (or, depending on how you