Written by Nick Glass, CNN

Royal Ascot has long been a terrific place for spotting celebrities. During Hollywood's Golden Age, Elizabeth Taylor, Rita Hayworth and Sophia Loren traveled to Berkshire, England, for the horse races, and in recent years, Helen Mirren, Eddie Redmayne, and Mo Farah have done the same.

But since it was founded more than 300 years ago, the royal family has been at the center of the event. Ascot is where they congregate to let their hair down -- while keeping their dress code-mandated hats firmly on, of course.

It happens with military precision. At 2pm sharp every day of the five-day meet, the royals come down the course in open horse-drawn landaus, along the straight mile by the grandstands. The royal procession was started in 1825 by King George IV, a lover of pomp and pageantry. This is probably the closest sighting we ever get of the royal family all together, much more intimate than those long-distance views of the balcony at Buckingham Palace.

Do we ever see the Queen more animated than at the races? Year after year, photographers have captured her uninhibited excitement as the horses cross the line -- especially when she has a winner. The same often goes for the rest of the royal party, caught open mouthed, jumping up and down. (Princesses Beatrice and Eugenie in particular seem to excel at this.)

Princess Elizabeth, left, and Princess Margaret arrive at the Royal Ascot grandstand in 1949. Credit: PA Images/Getty Images

Racing at Ascot was first established in 1711 by a horsey monarch, Queen Anne (recently brought to life by Olivia Colman in "The Favourite." ) She was out in the forest near Windsor Castle when her carriage swept into a clearing. It was large and flat enough for racing. And so that was that: The first race, Her Majesty's Plate, was ridden just a few months later.

Immediately following WWII, the big attraction was the two princesses, Elizabeth and Margaret. On several occasions, Princess Margaret turned up with her equerry boyfriend, Group Captain Peter Townsend, in tow.

In 1960, Queen Elizabeth II was photographed privately taking a gallop down the course with friends. It's her local course, a mere six miles from Windsor. She has been passionate about horses and racing all her adult life and has long bred thoroughbreds.

Royal Ascot -- so they say -- is her favorite week of the year, and it's easy to see why. The royal colors (purple and scarlet silks, black velvet with gold fringe) have been in the winning enclosure at Royal Ascot more than 20 times during her reign. In 2013, she made history when her horse Estimate won the Gold Cup at Ascot, making her the first reigning monarch to win the prestigious prize the race was established in 207 years earlier.

Princesses Eugenie and Beatrice arrive at Ascot Racecourse in 2008. Credit: Mark Cuthbert/UK Press/Getty Images

Then, in the late '80s and early '90s, it was another then-inseparable pair, Princess Diana and the Duchess of York -- Diana and Fergie -- laughing and flitting around the paddock.

Now, of course, we wait to see what the present batch of royals will be doing. Will the Duke and Duchess of Cambridge be sharing a carriage with the Duke and Duchess of Sussex? What will Kate and Meghan be wearing?