Sienna Miller Celebrates Alan Cumming's Birthday With Studio 54 Party!

Sienna Miller joined pal Alan Cumming for the ultimate birthday bash!

The duo stepped out for the party on Sunday night (January 27) at The Water Tower at The Williamsburg Hotel in Brooklyn, NY.

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In honor of Alan‘s 54th birthday, he hosted a Studio 54 themed party and got totally decked out in a leopard print suit and wig!

“I had the best Studio 54 themed birthday party at @thewatertowerbar of the @wburghotel last night, and then we headed over to @clubcumming for more japes! ‘Twas a good night!” Alan wrote on his Instagram.

Check out the photos below…