The world’s oldest annual marathon and one of its most prestigious, the Boston Marathon nearly swallows the city whole year after year, drawing runners from all over the world and spectators from every corner of the region. The race, which starts in the suburb of Hopkinton and ends in Boston’s Back Bay, happens every year on Patriot’s Day (the third Monday in April), and is by far New England’s most-watched sports event.

The size of the race itself is noteworthy, too; it boasts an average of 20,000 official runners (many other participants, called “bandits,” run unregistered) — remarkable since the race’s qualification requirements are unusually high (simply qualifying has become a bragging point in its own right). The exacting standards for entrance aside, the marathon is also famous for its tough course — the difficulty of which literally peaks at Heartbreak Hill. One of a series of hills in Newton, Heartbreak is feared not so much for its height, but because runners reach it between the 20th and 21st miles of the race — a time when they’re likely to be already low on energy.

Challenging as running the race is, viewing it can be tricky, too, given the crowds of spectators that average 500,000 every year. Sidewalks outside the city tend to have more viewing space, but if you’re determined to get as close to the finish line as possible, the best way is to go early in the day to one of the restaurants or bars close to the finish line in Copley Square. By late afternoon, they become loud, boisterous parties full of revelers. But then again, by the end of the race, so have all the blocks surrounding the finish line.