Inside publishing heiress Lydia Hearst's opulent bachelorette

Lydia Hearst made the most of her family's assets over the weekend as she celebrated her bachelorette party at Hearst Castle in California, The heiress to Hearst Magazines, which was established by her great-grandfather William Randolph-Hearst, was joined by 18 of her closest girlfriends at the historic venue.

Her nearest and dearest included actresses Cara Santana and Jillian Murray, Seth Green's actress wife Clare Grant and Lydia's former Gossip Girl co-star Michelle Trachtenberg.

Lydia, who is set to marry her TV host fiancé Chris Hardwick (The Talking Dead) in a couple of weeks, shared a poignant message on Instagram following her "magical" hen do.

TAP TO VIEW GALLERYLydia Hearst at Hearst Castle Lydia Hearst celebrated her hen do at Hearst Castle, California

The model thanked her girlfriends – "passionate and genuine women" – for their friendship and support, and added that she was "fortunate to be able to say that I am marrying the love of my life".

"Thank you for celebrating this pivotal moment of my life and share in the love I have for my incredible fiancé," she wrote. "This weekend was truly magical and would not have been the same without each and every one of you. I love you all!!!"

Tour group sitting in rows of chairs The group were given a VIP tour of the historic venue

Lydia, 31, opened the doors of Hearst Castle to her group of friends. The hen do included a VIP tour of the landmark, complete with a swimming session in the usually-closed Roman pool. The group were even joined by hunky 'Baywatch' lifeguards.

The girls also stepped inside the opulent film screening room, with Michelle Trachtenberg sharing a snap. "Private tour of the #hearstcastle? Don't mind if I do. This is the magical screening room. Just another awesome activity for @lydiahearst's #bachelorette weekend," she wrote.

Michelle Trachtenberg on horse Michelle Trachtenberg shared a photo from their horse-riding session

The Gossip Girl alumna, 30, also posted a photo from the girls' horse-riding session at Hearst Ranch, which was accompanied by an alfresco meal with views of the beach.

Michelle was clearly having far too much fun on the hen do as she posted some late Instagram snaps, writing: "Been so busy enjoying @lydiahearst's fabulous #bachelorette weekend, I haven't had a moment to post, because I've been in the moment, stay tuned for more. Started at the #MadonnaInn for breakfast..."

bedroom of the castle The girls stayed in the opulent castle over the weekend

Lydia looked to have had the time of her life on her hen. A few weeks ago the future Mrs gave fans a sneak peek of her beaded wedding dress, designed by Christian Siriano.

"When I put it on, it brought tears to my eyes," she wrote on Instagram. "And while wearing it, I couldn't help but remember my very first date with @hardwick, how I felt the first time he held my hand, and the very moment I knew that I loved him. And now, I can't help but imagine walking down the aisle and saying 'I do.'"

dining room at Madonna Inn The hen do kicked off with breakfast at Madonna Inn

The heiress currently spends her time between Los Angeles and New York City, focusing on modelling and acting.

After university, Lydia was discovered by fashion photographer Steven Meisel in 2003 and put on the cover of VOGUE Italia in April 2004. She has since starred in countless fashion magazines around the world.

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