Jennifer Aniston and Justin Theroux were spotted celebrating their engagement with Aniston's best friend and former "Friends" co-star, Courteney Cox, this week.

The trio let the good times roll at the Sunset Tower Hotel in Los Angeles, which is a special place for the couple, as it's the first restaurant were Aniston and Theroux were spotted having dinner together, Us Weekly reported.

During the fun times, an onlooker said Aniston "looked absolutely amazing. She was glowing."

The restaurant's waitstaff brought over a free bottle of Dom Perignon to the table "to congratulate her on her engagement," and everyone appeared to be enjoying themselves as the evening turned into a small celebration.

Aniston, Cox and Theroux weren't the only famous faces on hand in the hotel that night. Also present were Tom Hanks, Rita Wilson, Tom Ford, Amy Poehler and Seth Meyers.

The last time Cox and Theroux had dinner together, it was sans Aniston. The pair met up, along with pal Laura Dern, on July 30, just before Theroux popped the question to Aniston. Jen was on set in North Carolina, but Theroux asked her friends for their blessing before asking Aniston to get hitched.

Reports say Aniston has already begun planning her big day. She's already decided she doesn't want a prenuptial agreement, and she's reportedly considering asking Spice Girl Victoria Beckham to design her bridal gown.