Simon Cowell's 50th Birthday Bash Worth $1 Million

It was no simple birthday bash for Simon Cowell's 50th on Saturday.

Details of Simon Cowell's super-posh 50th birthday party Saturday night outside London.

Saturday night 350 guests celebrated Simon Cowell's 50th birthday (which doesn't arrive till October 7). The luxe affair took place on a mansion estate in Herfordshire, a lush English countryside location not far from London's city limits.

Decorations were minimalist but elegant with crystal and white linens adorning the venue, and sushi and "simple foods" were served, according to one source.

Leona Lewis is said to have performed, and the guest list included stars like Elton John, Donald Trump, Kevin Spacey, Kate Moss, Danii Minogue and Girls Aloud superstar Cheryl Cole. At the last minute Paula Abdul bowed out because of the flu, as she wrote on Twitter late Friday night, "Not making it to the party after all. Dr. said no way. I'm bummed by I'll survive. Goodnite everyone."

Sources say that Cowell spent approximately $1.6 million on the extravaganza, but did not want his guests presenting him with lavish gifts. Plus, attendees didn't have to worry about coming and going from the affair -- Cowell reportedly hired a limo to shuttle them.

Happy birthday, Simon Cowell! Read which of Simon's American Idol co-stars wants to sit by Ellen DeGeneres the most.