Simon & Garfunkel were an American folk rock duo consisting of singer-songwriter Paul Simon and singer Art Garfunkel. They were one of the most popular groups of the 1960s, and were viewed as counterculture icons of the decade's social revolution, alongside artists such as the Beatles and Bob Dylan. Their biggest hits—including "Mrs. Robinson" (1968), "The Boxer" (1969), and "Bridge over Troubled Water" (1969)—reached number one on several charts worldwide. Their often rocky relationship led to artistic disagreements, resulting in their 1970 breakup. Their final studio record, Bridge over Troubled Water, was subsequently their most successful, becoming one of the world's best-selling albums. They have reunited several times since their split, most famously for 1981's "The Concert in Central Park", which attracted more than 500,000 people, the seventh-largest concert attendance in history.