Michael Jackson's 53rd Birthday: The World Celebrates

Musical tributes, flash mobs and tweets — the King of Pop might be gone, but he's far from forgotten

Michael Jackson would have turned 53 on Monday if not for his untimely death on June 25, 2009.

And though the musical legend has left this world forever, the King of Pop's life is being celebrated throughout the country in a variety of ways.

The big celebration is occurring in Jackson's birthplace in Gary, Ind., where the city is holding a four-day celebration that began over the weekend.

The Chicago Tribune reported that the extended bash — marked by musical performances and a circus — drew hundreds of fans over the weekend, and was attended on Saturday by Jackson's family, including his 13-year-old daughter, Paris, as well as his sons Prince, 14, and Blanket, 9, and his father Joe.

Jackson's mother, Katherine, was also on hand for the festivities on Sunday, TMZ reported.

Those who couldn't make it to Indiana still managed to find ways to celebrate.

In San Francisco, the singer's birthday was marked with a flash mob dancing to "Thriller." The semi-organized dance performance wound its way from the city's Ferry Plaza to Union Square, into the Mission District's Dolores Park and finally into the Castro District.

Watch footage from the birthday flash mob in the video (story continues below video).

Jackson's influence on musicians is probably inestimable, and quite naturally the artists who've drawn inspiration from him are remembering him on his special day.

Former Tribe Called Quest rapper Q-Tip performed a special tribute to Jackson at his concert in New York City's Irving Plaza on Saturday.

"Michael Jackson was a huge influence on my music and was an inspiration to me and so many others," Q-Tip told the press. "I want to bring people together to celebrate the man, his music and his legacy that will undoubtedly live on forever!"

Meanwhile, Chris Brown weighed in on the milestone Monday, writing on his twitter account, "Happy birthday Michael Jackson!!!! Your [sic] the greatest!"

The celebration of Jackson's life and musical contributions with the end of his birthday Monday. Michael Forever — The Tribute Concert will take place on Oct. 8 at the 74,500-seat Millennium Stadium in Cardiff, Wales.

Though the production has been beset by problems, artists including Christina Aguilera, Cee Lo Green, the Jackson Brothers, Leona Lewis and Smokey Robinson are scheduled to perform.

Not everyone is joining in the celebration of the singer's life, however.

The Los Angeles Times reported that the defense team for former Jackson doctor Conrad Murray filed papers in Los Angeles Superior Court Monday indicating that they plan to paint Jackson as a hopelessly hooked addict who was constantly "on the hunt" for the anesthetic propofol.

The papers indicate that Murray's defense team will enlist the testimony of numerous Jackson associates  — including friends, members of his medical team, and even Grace Rwaramba, the nanny to Jackson's children, in order to make the case that the singer was hooked on propofol and other drugs.

Jury selection for Murray's nvoluntary manslaughter trial is scheduled to begin Sept. 8.