By Jennifer Davis
Updated Apr 22, 2016 @ 10:45 am
2016 - Oscar de la Renta
Credit: John Stillwell - WPA Pool/Getty Images

Queen Elizabeth's 90th birthday celebrations are still going strong! Today, President Barack Obama and First Lady Michelle Obama arrived at Windsor Castle to honor the reigning monarch, and the couple looked as stylish as ever as they greeted the royals for a belated birthday lunch.

For the royal occasion, the FLOTUS chose a purple Oscar de la Renta dress featuring an intricate lace overlay, which she styled with a black clutch and low-heeled pumps. Meanwhile, Queen Elizabeth stayed true to her love of monochromatic looks, wearing a light blue skirt suit. She finished off the look with her signature handbag and lace pearls. Not to be outdone by the ladies, both Prince Philip and President Obama looked dapper in suits and colorful ties.

This isn't the only royal get-together for the Obamas. Later today, they'll dine with Prince William, Princess Kate, and Prince Harry at a special dinner at Kensington Palace. We can't wait to see what Kate and Michelle will wear!