On Monday, Paris Hilton was thinking back to a, well, simpler time.

The heiress took to Twitter to commemorate the infamous reality TV show that she and Nicole Richie starred in from 2003 to 2007.

"Happy 15 Year Anniversary to #TheSimpleLife," she wrote on Instagram while sharing the promo image of her standing next to her former BFF and her late pet Tinkerbell.

"Loves it! So many fun, amazing & hilarious memories with Nicole," Paris continued. "Love that this show is so timeless & iconic. And that it has brought so much happiness and laughter to people around the world. And the #Legend Tinkerbell who I love & miss very much. #TheOGs."

The premise of the show was simple: Paris and Nicole give up their glamorous Hollywood lives to tackle various jobs all over the country. On Dec. 3, Paris posted a highlight reel of sorts from the show.

"I think Nicole and I definitely started the whole reality TV thing," she told In Touch in 2015. In discussing the different between reality TV now versus when she was doing it, she said, "It seems like the shows are more about drama now than having fun. Nicole and I were just having a lot of fun."

At the time, she said she would be open to doing a "Simple Life" reunion.

"You know, I order the show on my Apple TV all the time, and I watch it and laugh," she said. "There are so many crazy memories. So yeah, I would definitely be into a reunion."

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She recently told Gay Times she turned down a reboot of the series due to her schedule.

"It changed my whole life since it was the first of its kind," she told the magazine. "There really was nothing out there like it in the world. After that show, I got to go all around the world and it really just started my career in this business."

Still, despite having love for the show, she said she wasn't accurately portrayed at all… but that was all by design, too.

"I think the biggest misconception is that people still think I'm the ditsy blonde from 'The Simple Life,'" she said. "What most people don't know is that it was a character that I came up with for the show and created for several reasons."