Thousands of people are running around some of the D.C.-area’s most iconic sights and landmarks this weekend for the 49th annual Marine Corps Marathon.

The 26.2-mile race began Sunday morning and road closures are in place for the one of the largest marathons in the U.S. and the world, earning it the nickname “The People’s Marathon.”

• Wish you had signed up for the Marine Corps Marathon? Here’s how to prepare for next year’s

Here’s what you need to know.