The elegant brunette is said to have spent more than two hours at the fashion house, and was pictured hugging a seamstress as she left.
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Amal Alamuddin was seen visiting the Alexander McQueen headquarters
It has sparked reports that Amal, 36, has commissioned a McQueen bridal gown for her wedding to the Hollywood star. There was previously speculation that she might choose a designer from her native Lebanon – Elie Saab or Zuhair Murad.
Alexander McQueen is one of London's leading fashion houses – and given that Amal is based in the British capital, it is perfectly placed to craft her wedding gown.
Furthermore, it is synonymous with timeless, elegant designs, much like Amal's personal style.
The Duchess of Cambridge in her beautiful wedding gown
Of course, it was McQueen's creative director Sarah Burton that Kate Middleton chose to create the fairytale dress she wore to marry Prince William.
That design has gone down in the history books as one of the most breathtaking and iconic royal wedding gowns - so it is little wonder that Amal might choose to follow in the Duchess' footsteps.
Sarah previously described working with Kate for the royal wedding as a "highlight" of her career.
Alexander McQueen creative director Sarah Burton
"She looked so beautiful," said the designer, who received an OBE for her work. "She's got such an amazing sense of grace and style, it was quite easy to make her look good. For me, it was a huge highlight of my career. It came completely out of the blue, it was all very exciting and I felt very privileged."
Amal and George are expected to tie the knot later this month at his villa on the banks of Lake Como.
George Clooney and Amal Alamuddin are expected to tie the knot later this month
According to reports, the groom has been very hands-on when it comes to planning the perfect day for his bride.
"Everyone has been so impressed with how involved he is with everything," an insider told E! News. "He really is a fantastic man and it's very obvious from his actions how much he loves Amal."