In 1974, Joel recorded his second Columbia album in Los Angeles, Streetlife Serenade. His manager at the time was Jon Troy, an old friend from the New York neighborhood of Bedford-Stuyvesant; Troy would soon be replaced by Joel's wife Elizabeth. Streetlife Serenade contains references to suburbia and the inner city. It is perhaps best known for "The Entertainer", a No. 34 hit in the US. Upset that "Piano Man" had been significantly cut for radio play, Joel wrote "The Entertainer" as a sarcastic response: "If you're gonna have a hit, you gotta make it fit, so they cut it down to 3:05." Although Streetlife Serenade is often considered one of Joel's weaker albums (Joel dislikes it himself), it contains the notable songs "Los Angelenos" and "Root Beer Rag", an instrumental that was a staple of his live set in the 1970s.  In late 1975, Joel played piano and organ on several tracks on Bo Diddley's The 20th Anniversary of Rock 'n' Roll all-star album.  Disenchanted with Los Angeles, Joel returned to New York City in 1975 and recorded Turnstiles, the first album he recorded with the group of hand-picked musicians who became the Billy Joel Band. Produced by James William Guercio (then Chicago's producer), Turnstiles was first recorded at Caribou Ranch with members of Elton John's band. Dissatisfied with the result, Joel re-recorded the songs and produced the album himself.  "Say Goodbye to Hollywood" was a minor hit; Ronnie Spector recorded a cover as did Nigel Olsson, then drummer with Elton John. In a 2008 radio interview, Joel said that he no longer performs the song because singing it in its high original key "shreds" his vocal cords; however, he did finally play it live for the first time since 1982 when he sang it at the Hollywood Bowl in May 2014. Though never released as a single, "New York State of Mind" became one of Joel's best-known songs; Barbra Streisand and Tony Bennett have each recorded covers (Bennett's a duet with Joel on Playing with My Friends: Bennett Sings the Blues). Other notable songs from the album include "Summer, Highland Falls", "Miami 2017 (Seen the Lights Go Out on Broadway)", "Say Goodbye to Hollywood", (a live version of which became a Top 40 hit), and "Prelude/Angry Young Man", a concert mainstay.

Answer this question "what was the turnstiles?" by extracting the answer from the text above.
the first album he recorded with the group of hand-picked musicians who became the Billy Joel Band.