Annual Events: For many world-class runners, the Boston Marathon is the pinnacle of their racing career. This 26.2 miler is a course that tests your endurance and is lined with crowds cheering for each and every runner to cross the finish line. The real attraction comes from watching with friends. Marathon Monday, the 3rd Monday in April, is a lively sidewalk celebration that starts in Hopkinton and continues all the way to the Boylston Street finish line in Boston's Back Bay. Grab a window seat at a bar, hang out on the sidewalk with the crowds or linger at the finish line to greet those who complete the course, just don't miss a Boston Marathon.