Paris Hilton at 'House of Y2K' Collab Pop-Up, Celeb Friends Show Support

Paris Hilton is kicking off her latest project in a massive way ... bringing some of her closest celeb pals together and, naturally, rocking a pretty iconic outfit for the event.

Paris was front and center for the opening of her "House of Y2K" pop-up Thursday night on Melrose in L.A. -- it's an interactive experience that dives deep into how trends and shopping evolved over the last 20 years.

Of course, it's not just a history lesson ... Paris' personal wardrobe is also on display, including some of her most famous 'fits.

As for her outfit choice Thursday night ... Paris rolled up with something identical to what she wore back in 2002 at her 21st birthday party -- talk about a blast from the past.

Some of her closest gals showed up to support Paris ... including her mama Kathy Hilton and "The Real Housewives of Beverly Hills" star Faye Resnick.

Of course, Paris also had Kris Jenner by her side ... who has been friends with Kathy for decades ... and don't forget the early 2000s, when Kim Kardashian and Paris were painting the town red together.