Queen Elizabeth II, the Queen of the United Kingdom, Canada, Australia, and New Zealand, and the Head of the Commonwealth, celebrates her 90th birthday on Thursday, April 21, 2016. England has been celebrating the big day since the beginning of the month, and it is expected to continue till the end of June.

The Royal Mint even produced a commemorative £5 coin to mark the special occasion. The coin, designed by sculptor Christopher Hobbs, features a garland of roses, tipping the hat to the Queen's love for flowers. You can purchase the coin from The Royal Mint website for £20, but they are limited to three per household.

The Queen herself will celebrate her 90th birthday at Windsor Castle, where she will unveil a plaque. It will mark the start of a four-mile Queen's Walkway, reports the Telegraph. The walkway will reportedly connect 63 points of interest in London, thereby recognising the Queen's long-lasting monarchy, which has lasted over 63 years.

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Following the unveiling, the Queen and Duke of Edinburgh will go on a walkabout to meet members of public, many of whom have camped overnight to get a glimpse of their Queen. In the evening, she will light the first of 1,000 beacons spread across the country to celebrate her birthday.

Queen Elizabeth will also have a private celebration at Windsor Castle in the evening, which will be attended by the Duke and Duchess of Cambridge. Many loyal fans of the royals will know that Prince William and Kate Middleton have already celebrated the Queen's 90th birthday once at the British High Commissioner's office in New Delhi during their recent India tour.

A series of three photographs of the Queen was also released in celebration of her birthday. One of them showed the matriarch surrounded by her two grandchildren and five great-grandchildren, including Prince George and Princess Charlotte.

In celebration of her birthday, we have compiled a few of Queen Elizabeth's photographs over the years. Check them out in the slide-show above.