It's some 400 miles from Harvard Square to Capitol Hill, but when Rory Stewart made the trip last month, he chose an unlikely mode of transport: He took a plane. Stewart is an inveterate, epic walker. He spent part of this past summer strolling the 150 miles from Crieff to Penrith in his native Scotland. More impressively, in 2002, not long after he quit his job with the British Foreign Office, he walked across Afghanistan, a 600-mile jaunt that served as the basis for his best-selling book The Places In Between. Indeed, his Afghan adventure was only one leg of a 6,000-mile journey by foot through six Asian countries that took nearly two years to complete.