Hey Upper East Siders, Gossip Girl here, and Serena van der Woodsen is getting a little nostalgic. On Sept. 21, Blake Lively celebrated the 18th anniversary of her breakout series Gossip Girl by posting never-before-seen throwback photos with many of her former co-stars, including her ex-boyfriend, Penn Badgley , and the late Michelle Trachtenberg .

Taking to Instagram, the actor shared a slideshow of snapshots from the cast’s time on and off set, some of which were developed and displayed on a wooden table. Highlights include Polaroids with on-screen BFF Leighton Meester , a bouncy house photo with Chace Crawford, wearing matching outfits with Ed Westwick, and funny face photos with Badgley and Trachtenberg.

“The summer gossip girl turned 18...,” Lively captioned the post.

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