The Beatles and Cassius Clay The Beatles and Cassius Clay

Their timing was as perfect as their music. The Beatles' first trip to America in February 1964, just a few weeks after the assassination of President John F. Kennedy, brought a devastated nation some desperately needed joy and excitement — and that's just one of the many seismic events in the new American Experience documentary 1964, premiering Tuesday on PBS (8/7c, check local listings).

What a year. President Lyndon Johnson spearheaded the landmark Civil Rights Act and launched a war on poverty, students at U.C. Berkeley were rising up in revolt, millions flocked to the futuristic New York World's Fair, Betty Friedan was triggering a feminist firestorm with The Feminine Mystique and Bob Dylan told us — as if we needed further proof — that The Times They Are a-Changin'.

Based on the Jon Margolis book, The Last Innocent Year: America in 1964, the program is narrated by Oliver Platt and features a terrific but little-known story about the day the Beatles met up with the year's other intergalactic superstar, Cassius Clay — who would soon announce his conversion to Islam and change his name to Muhammad Ali.

Check out this exclusive clip of the Fab Five's fascinating meeting! 

Exclusive Sneak Peek of PBS's American Experience

Watch The Beatles' meeting with Cassius Clay