Princess Diana Spencer on Instagram: “39 years ago today on Wednesday, July 29, 1981, Lady Diana Spencer, a 20 year old kindergarten teacher, married Charles, Prince of Wales,…”

Take a look back at their intimate civil ceremony and marriage blessing in Windsor.

Insider has gathered the best rare photos from the event which marked Diana's entrance into the royal family almost four decades ago.

Take a look at these romantic pictures from the royal wedding of the century—the day Lady Diana Spencer and Prince Charles got married at St Paul's Cathedral.

Prince Charles and Princess Diana returning to Buckingham Palace after their wedding, July 29, 1981.

The Duchess of Cambridge has been invited to the event six months after giving birth to her second child

Here is what everybody's favorite royals were doing every year from 1950 to the present.