There's flying the green flag for Ireland, and then there's Ruth Negga's breathtaking outfit at last night's Academy Museum of Motion Pictures Opening Gala in Los Angeles.

After over a year of cancelled award shows and virtual ceremonies, we're finally getting caught up with all the glitzy events we've been missing since last year, and Negga made her red carpet comeback with a bang.

The Irish star shone as she walked down the green carpet, rubbing shoulders with a host of celebrities as they gathered to celebrate the opening of the Academy Museum of Motion Pictures, an event they've been waiting 10 years for.

Photo: Getty

Due to open to the public on Thursday, 30 September, some of Hollywood's biggest names gathered to christen the museum, including Oscar winners, industry heavyweights, producers, directors and more.

The theme of the night was Cocoanut Grove, an homage to the iconic Old Hollywood nightclub that hosted generations of mega stars. Tom Hanks, Nicole Kidman, Lady Gaga and Cher were just some of the big names partying the night away.

For the glamorous occasion, it's no wonder Ruth opted for a stunning vintage gown, styled by celebrity stylist Karla Welch and pulled from the eye-wateringly lavish collection of Shrimpton Couture, a renowned vintage archive curated by Cherie Balch.

Ruth wore a piece by Arnold Scaasi, a Canadian designer best known for designing the suit worn by Barbra Streisand the night she won the Oscar for her role in Funny Girl.

We need your consent to load this Instagram contentWe use Instagram to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences

The gown, from 1992, features a long A-line skirt embellished with intricate floral motifs in crystals. What gave it the wow factor, however, were the dramatic voluminous sleeves in a rich green velvet and the structured v-neck bustline that hugged Ruth's figure.

She accessorised her look with jewellery from Jennifer Meyer, and wore her hair slicked back into a modern but intricate twist that curled at the nape of her neck. Her makeup was dark and glamorous, with a deep red lip adding a touch of Old Hollywood drama.

Posting on Instagram, Balch spoke about the gown's "major Hollywood connection", as Elizabeth Taylor wore a version of the gown, minus the ornate green velvet bust and sleeve detail.

She wrote: "I would bet my bottom dollar that both Arnold and Elizabeth are beaming from wherever they are to see Ruth carrying their part in its history forward so very very beautifully."

Photo: Getty

Ruth wasn't the only star to pull out all the stops however, as Lady Gaga stunned in a black column dress and periwinkle blue wrap by Schiaparelli, Cher turned heads in a typically eye-catching black, white and leopard print patchwork look by Dolce & Gabbana, and Nicole Kidman sizzled in a red and orange floral number by Rodarte.

Photo: Getty

Click through the gallery above to see all the celebrity red carpet fashion from the Academy Museum of Motion Pictures Opening Gala in Los Angeles.