Twenty years ago today, the 180th and final episode of NBC's "Seinfeld" was performed at CBS

As with the other episodes performed at CBS Radford Studios' Stage 9, the largest on the lot.

Seinfeld was never meant to be a show about nothing, as it is often described, but rather the adventures of a comedian getting material for his show. Jason Alexander threatened to quit "Seinfeld" in the third season. After the table read of "The Pen", which features only Jerry and Elaine, Alexander pulled Larry David aside and said "if you write me out again, do it permanently." In 9 seasons, that was the only episode he wasn't it.

Jerry Seinfeld offered to voice a character on South Park, but later declined after Matt Stone and Trey Parker had only offered him the part of "turkey #2"

The motto among writers and cast of Seinfeld was "no hugging, no learning" (one writer said, "There will never be 'a very special episode' of Seinfeld"). In one scene during the episode "The Secret Code", Kramer tells Jerry, "Well, at least you learned something." Jerry replies, "No, I didn't."

Roger Ebert permanently retired the word "midget" from his column after Danny Woodburn (aka Kramer's friend Mickey on Seinfeld) wrote to him and called it a "hate word" for little people.

The "sexy wake-up service guy" who called Elaine on Seinfeld was Peter Dinklage (Tyrion on Game of Thrones).

Newman's first name was never revealed in Seinfeld

When aired, that finale was watched by 76.3 million (58% of all viewers that night) making it the fourth most watched regular series farewell in U.S. TV history, [behind M*A*S*H, Cheers and The Fugitive.]

Frank Sinatra's death coincided with the Seinfeld series finale. Sinatra's ambulance was able to arrive to his house and then the hospital quickly because of low traffic due to much of Los Angeles being inside to watch the show

"Seinfeld" has made US$2.7 billion on reruns through June 2010 since it went off the air in 1998.