As far as happy marriages in Hollywood are concerned, "Iron Man" star Robert Downey Jr. thinks that his union with producer wife Susan is high up on the list.

As they celebrated their 10th wedding anniversary recently, the actor shared a photo of himself with his wife and captioned it, "A perfect 10. Happy Anniversary, Mrs. Downey!"

Downey might think that their marriage is pretty amazing, but he is not the only one who has that opinion, according to the Sydney Morning Herald.

"Sherlock Holmes" director Guy Ritchie has praised their union as the most "perfectly symbiotic" marriage in Hollywood.

"The reason I call them perfectly symbiotic, it's that they each represent the other side of each other's coin," Ritchie explained. "There's no clashing over the same space, although they're always looking in the same direction. It's a very rare thing they have."

Downey, 50 and Susan, 41 met on the set of "Gothika" back in 2003. Sparks did not fly immediately on the side of Susan, who viewed Downey as someone "interesting but weird," but Downey was already interested in her on the get-go.

"We were up in Montreal prepping for 'Gothika,' and we had lunch with the director and Halle Berry," Susan recalled of their first encounter. "Everybody else ordered Japanese, but Robert told us how oatmeal was the 'superfood'. He brought his own packets of oatmeal to have at lunch. And he had this box of various herbs and stuff. And then he started doing these yoga moves. I mean, he was interesting but weird."

For his part, Downey tried asking Susan out for three times until she finally said yes. Within just three months of dating, Downey already proposed marriage, even though he has not yet divorced from his then wife model and singer Deborah Falconer, whom he wed back in 1992. They even have a 21-year-old son together named Indigo.

Susan did not say yes immediately to Downey's proposal, but when she did, she insisted on a two-year engagement. The couple got married on August 2005 in the Hamptons.

Downey and Susan have two children together - a three-year-old son named Exton and a one-year-old daughter named Avri.

Before they met each other and got married, both Downey and Susan actually led very different lives.

"I was very focused, driven, rigid, work-oriented," Susan said of her life before Downey. "I didn't care about having a family or making a home. I didn't think about kids. It's not that I didn't want those things, I just didn't think about them. And then I had someone who came in as a tornado, this creative, beautiful ball of insane energy and passion. And it completely opened me up."

As for Downey, he suffered from a heavy substance abuse problem that almost cost him his career, and he credits his marriage for helping him overcome it and raved about the time spent with Susanas his "great transition."

"She is the font of all good things," he said about his wife.