Hats off to the new Duke and Duchess of Sussex!

As wedding bells rang at last for Meghan Markle and Prince Harry, many female guests gave their nod of support in style with a fabulous array of hats and fascinators. In fact, donning a headpiece is actually one of the strictest royal dress code rules.

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Queen Elizabeth II and Prince Phillip at St. George's Chapel at Windsor Castle for the wedding of Meghan Markle and Prince Harry. (AP)

“Hats are a sign of festivity for a British wedding. They are kept on inside the church, but people should be careful of the people sitting behind them,” Plaza Hotel etiquette expert Myka Meier told The Associated Press. “It’s not the Kentucky Derby. No huge brims. Nothing too high,” she said, of the royal wedding.

From Oprah Winfrey’s blooming blossoms and Amal Clooney’s timeless look to Doria Ragland’s sweet beret and Camilla Parker Bowles’ over-the-top number, take a peek at some of the greatest hats and fascinators spotted at Windsor Castle on May 19.

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Prince Charles escorts Doria Ragland and Camilla Parker Bowles into the church. (AP)

Oprah Winfrey arrives at St. George's Chapel at Windsor Castle for the wedding of Meghan Markle and Prince Harry. (AP)

Amal and George Clooney head to the ceremony at St. George's Chapel. (AP)

Serena Williams and Alexis Ohanian were all smiles for the May 19 festivities. (AP)

The Princess Royal arrives at St. George's Chapel at Windsor Castle for the wedding of Meghan Markle and Prince Harry in Windsor, England, May 19, 2018. (Reuters)

The Duchess of Camrbrige stepped out in a floral-decked hat. (AP)

Princess Beatrice and Princess Eugenie opted for decidedly more conservative hats than those they sported to the Duke and Duchess of Cambridge's 2011 wedding. (Reuters)

Abigail Spencer and Priyanka Chopra arrive at the wedding. (Reuters)

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Charles Spencer, 9th Earl Spencer, and Karen Spencer arrive at the wedding of Prince Harry to Meghan Markle. (Reuters)

Lady Kitty Spencer arrives at St. George's Chapel at Windsor Castle for the wedding of Meghan Markle and Prince Harry. (Reuters)

STAFF AT HOTEL WHERE MEGHAN MARKLE AND MOM ARE STAYING TOLD NOT TO WAVE AS THEY LEAVE, SOURCE CLAIMS