On Sunday, The King's Troop will perform in front of the Queen and it's taken months of training to get them ready.
The soldiers on horseback were first formed in 1946 to be a show piece during ceremonies of state. Simon Parkin went to see them rehearsing.
The Queen's 90th birthday celebrations in Windsor this weekend are set to be an event to remember. The offering will feature one and a half thousand performers from across the world, 900 horses, 25,000 spectators and a very special guest of honour.
We've met some of the acts taking part and we've been speaking to those who know the Queen personally.
Last-minute sound checks and rehearsals have been happening today in the main arena, ready for this evening's events. But the day started with the 73rd Royal Windsor Horse Show. Here's Mike Pearse.
Queen Elizabeth II (centre) has been attending the third day of the Royal Windsor Horse Show, which is held in the grounds of Windsor Castle in Berkshire. The next few days hold major celebrations to mark Her Majesty's 90th birthday.
More on the celebrations marking The Queen at 90.
The Royal Navy will mark the birthday of Queen Elizabeth II with a 21-gun salute at Fort Blockhouse in Gosport today.
The event is one of many taking place at military establishments across the country. At Portsmouth's Naval base, Royal Navy ships will celebrate with flags displayed along their sides.
"The Royal Navy in Portsmouth always celebrates the Queen's birthday in this way, but this year is obviously extra special as it marks such a significant milestone for Her Majesty."
Gurkha soldiers in Kent have been scaling the Leas cliff in Folkestone in their battle against litter.
The efforts of the Royal Gurkha Rifles 2nd Battalion is in honour of the Queen's 90th birthday, and is one of a series of clean-ups coordinated by Shepway District Council as part of the national 'Clean for the Queen' campaign.
It is being billed as a huge party for the Queen - a star studded show in the grounds of Windsor Castle, to mark her Majesty's 90th birthday.
Now it has been revealed the event in May, which will be broadcast live on ITV, will be hosted by Britain's most popular TV duo Ant and Dec. As Rachel Hepworth reports, preparations are well under way.
The interviewees are: Simon Brooks-Ward, Director of the Queens's birthday celebrations; the singer Katherine Jenkins; Pau Roach, Windsor & Eton town manager; and Julia White, Windsor Visitor manager.
The Queen's love of horses is well-documented and today she got to meet the next generation of equine vets as she officially opened a new state-of-the-art veterinary school in Guildford.
Her Majesty and the Duke of Edinburgh were also given a tour of the £45 million facility. The University of Surrey is aiming to deliver cutting-edge teaching and research.
The school boasts a large clinical skills facility and what the university says is one of the best veterinary pathology centres in Europe.
Watch Emma Wilkinson's report:
Interviewee: Professor Chris Proudman, Head of Veterinary School, University of Surrey.
The Queen has opened a new state-of-the-art veterinary school in Guildford.
Her Majesty and the Duke of Edinburgh were also given a tour of the £45m pound facility.
This latest investment means the University of Surrey will be able to deliver cutting edge teaching and research.
The Queen is opening a new £45 million veterinary school in Surrey today.
She will be joined by the Duke of Edinburgh for a tour of the University of Surrey's School of Veterinary Medicine in Guildford and will meet students.
The royal couple will meet Professor Noel Fitzpatrick, star of Channel 4's The Supervet, and see dogs that have benefited from prosthetic limb surgery. The new facility boasts one of the best veterinary pathology centres in Europe.
"We are hugely honoured to welcome Her Majesty and His Royal Highness to the University of Surrey.
The School of Veterinary Medicine further cements our position as a world-class institution that is delivering cutting-edge teaching and research from state-of-the-art facilities.
It will not only provide the next generation of sought-after veterinary graduates, but it will offer significant opportunities for collaboration between human and animal medical science professionals and public sector organisations."
The Queen was in Reading today to officially open the town's new railway station. £900 million has been spent on a major revamp which includes five new platforms, two entrances, a new link bridge and retail outlets.
Despite radical cuts to public spending after the last election the massive upgrade at Reading was given the go-ahead.
That's because the station is one of the most important hubs in the country with links to London, Gatwick, the south coast and the Thames Valley.
It's is also one of the most congested.
Our Transport Correspondent Mike Pearse was there for the Royal opening. and spoke to Robbie Burns from Network Rail, Mark Hopwood the Managin Director at First Great Western, and Reading East MP Rob Wilson.