The oldest annual marathon in the world, the Boston Marathon, returns to the streets of greater Boston on April 16, hosting amateur and elite runners alike as they make the 26.2 mile journey from Hopkinton to the finish line in Copley Square. Inspired by the marathon held at the first modern Olympics in 1896, the first Boston Marathon dates to the following year, and has grown by leaps and bounds over the decades, attracting thousands of race fans who line the course to enthusiastically cheer on the weary harriers every Patriots’ Day, a holiday honoring the beginning of the American Revolution in 1775. A popular precursor to the race taking place April 13–15 that also acts as a pick-up site for marathoners’ bib numbers is the John Hancock Sports & Fitness Expo (617-439-7700, sportsfitnessexpo.com), which this year has relocated to the Seaport World Trade Center (200 Seaport Blvd.).