“The Hub,” “Beantown,” “Baaahstin” – call it what you will, New England’s largest city exists to be explored. Its colonial-era architecture, vibrant seafaring heritage, and irrepressible Yankee character make it one of the country’s most distinctive locales. Yet for all its big-city amenities – world-class restaurants, museums, and shops – Boston remains surprisingly compact and eminently walkable.