Songfacts®:

• Like his earlier hit "Strangers in the Night," this ballad from Frank Sinatra was based on a composition by German musician Bert Kaempfert. Sinatra hated the former tune but it brought him enormous success, so it's not surprising he revisited Kaempfert's catalog for his 1967 album The World We Knew with the "Strangers" team, arranger Ernie Freeman and producer Jimmy Bowen, back on board. But according to Bowen, it was Kaempfert's testy melodies that piqued Sinatra's interest.
  
  "Sinatra used to laugh at me. I think he was just challenging me to see if we could do it or not," Bowen told Sinatra! The Song Is You author Will Friedwald. "And he used to laugh because Kaempfert's melodies were always testy. 'Strangers In The Night' is not easy to sing. And 'The World We Knew' - oh, God, what a hard song to sing!'"
• Kaempfert's songwriting partner Herbert Rehbein is also credited as a composer on the track, along with lyricist Carl Sigman, a prolific songwriter who also wrote the English lyrics to songs like Frankie Laine's "Answer Me" and Percy Faith's "Till."
• Sinatra knew his way around a love song, especially of the brokenhearted variety. This time around, he's singing in anguish about a romance that was full of promise until the woman he loved fell out of love with him. At the time, his marriage to actress Mia Farrow was on the rocks - they separated earlier in 1967 and were divorced a year later in August 1968.
• This was Sinatra's sixth consecutive #1 hit on the Adult Contemporary chart (then called Easy Listening), where it held the top spot for five weeks.
• The World We Knew was Sinatra's second release of 1967. The first was Francis Albert Sinatra & Antonio Carlos Jobim, a critically acclaimed album that paired the pop singer with Brazilian composer Antonio Carlos Jobim (who wrote the music for the worldwide hit "The Girl From Ipanema" a few years earlier). The album features standards like "I Concentrate On You" and "Change Partners," reworked in the bossa nova style that Jobim made famous. It was nominated for Album of the Year at the Grammy Awards in 1968 but lost to The Beatles' Sgt. Pepper's Lonely Hearts Club Band.
• The album also includes Sinatra's hit duet with his daughter Nancy, "Somethin' Stupid."
• Jimmy Bowen spent most of the '60s as a producer at Sinatra's Reprise Records, where he also worked on hits for Dean Martin and Sammy Davis Jr. In 1968, he left to form his own Los Angeles-based label, Amos Records, which lasted a few years until a fortuitous move to Nashville rejuvenated his career. He took over the Nashville division for several major labels and produced big name artists like Dolly Parton, Waylon Jennings, George Strait, Reba McEntire, and Garth Brooks.
• This features renowned Los Angeles session musician Carol Kaye (of Wrecking Crew fame) on string bass and Fender bass.
• French singer-songwriter Charles Aznavour wrote a French-language version titled "Un monde avec toi" for singer Mireille Mathieu and orchestra leader Paul Mauriat.