Bridge Over Troubled Water marked the end of a lot of things, including the '60s, the partnership of one of the biggest acts of the era and that duo's reliance on the folk-rock sound they helped invent. But boy did they go out with a bang. The 1970 album is the most ambitious of Simon & Garfunkel's career, in both songwriting and production. Among other things, it prefigures Simon’s knowledge of and affection for international sounds and styles, a toolkit that would serve him well on 1986's Graceland. The Andean folk ensemble Los Incas on "El Condor Pasa (If I Could)", the Afro-inflected polyrhythmic base of "Cecilia" and the Brazilian bossa nova feel of "So Long, Frank Lloyd Wright" all take Simon & Garfunkel sailing far from their folkie past. Besides bearing a batch of huge hits that would remain ubiquitous on radio for decades, Simon & Garfunkel's swan song contains a pair of tunes destined to become dyed-in-the-wool American standards. The album's title track is an epic, gospel-swathed ballad of enduring compassion, with Garfunkel’s soaring vocal a tour de force that's widely regarded as his finest moment. "The Boxer", one of the few songs harking back to the duo's earlier sound, is the poignant jeremiad of a young man making his way in the big city; its "lie-la-lie" refrain became as resonant a part of the Simon & Garfunkel legacy as anything. Bridge was one of the era's biggest albums—both its scope and its success set a high bar for Simon's subsequent solo career. Fortunately he'd prove up to the task.