"Sweet Caroline" has been a tradition at Red Sox games for a long time. As Boston still recovers from the tragic Marathon bombing and subsequent capture of the accused bombers, it's become a symbol of unity and compassion being played in ballparks across the country by rivals including the New York Yankees.
On Saturday, Neil Diamond sang "Sweet Caroline" in person at Fenway Park for over 35,000 people before the Red Sox game against the Royals. Check it out:

Source: MLB.com