Ben Affleck and Jennifer Garner celebrated their nine year anniversary in Detroit on Sunday (29th June). The Hollywood couple have been spending time in the city as Affleck films his upcoming blockbuster movie, Batman v Superman: Dawn of Justice.

Instead of jetting back to L.A. to celebrate their anniversary in the company of their celebrity friends, the couple chose to roll out a little old school romance and go on an intimate dinner date to a local Detroit restaurant, Bistro 82, a fine-dining establishment in Detroit.

Justin Near of Near Perfect Media, which represents the bistro's AFB Hospitality Group, spilled the beans on the couple's appearance, saying that they arrived in the early evening and stayed for an hour before going on elsewhere. "A lot of people did a double take," Near told ABC News. "It was just the two of them, just like any other couple celebrating their anniversary."

"You might not even know it was them, they were dressed very casual and sat by the window," he added. "Ben had steak and fries and made a point to tell the waiter they were the best fries he's ever had ... they also had a nice bottle of wine."

Affleck, who was spotted in a button down shirt and jeans, is busy filming Zack Snyder's 2016 superhero sequel in the city. As the titular caped crusader, the Argo filmmaker has had some degree of bulking up to do to fit his character's heroic muscular proportions, which restaurant diners couldn't help but notice.

More: Ben Affleck recruits Matt Damon's fitness instructor cousin for Batman role.

"The guy is definitely ripped, that's for sure," Near said. "They just looked really engrossed in conversation with each other. The staff said they were a pleasure and really look forward to serving them again."

Ben, 41, and Jennifer, 42, have three daughters Violet and Seraphina and, son Samuel. Whilst Affleck was filming, Garner had been spending time with her three kids in her hometown of Charleston, W. Va. As she flew to Detroit for her anniversary celebrations with Ben, her children were reportedly flown home to L.A. with a Nanny.

More: Jennifer Garner "never understood" Ben Affleck's gambling obsession.

The couple's sweet and simple display of their union comes in spite of a recent rumour that Affleck put a stop to his wife's friendship with fellow actor Mark Ruffalo.

Ben Affleck Jennifer Garner
In Spite Of Recent Mark Ruffalo Rumours, Ben & Jennifer's Marriage Looked Strong On Their Anniversary.