USA: Tens of thousands of runners, including some of the world's best, and hundreds of thousands of fans are expected to hit the streets of Boston on Monday for the 119th running of the Boston Marathon.
Security will be high along the 26.2 mile course, in recognition of the bombing of the 2013 race, which killed three people and injured 264 in the one of the most visible attacks on US soil since Sept. 11, 2001.