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.
William the Conqueror chose the site for Windsor Castle. It was high above the River Thames, on the edge of a Saxon hunting ground. Construction work began in the year 1070. The castle, built by the Queen's ancestor, draws people to the town in Berkshire.
Princess Elizabeth and her sister Margaret spent the Second World War living there. It was a fortress to keep them safe. But to the Queen it was and always has been home.
As a young princess the Queen was given the Freedom of the Borough in 1947, the first woman to be given the honour.
ITV Meridian presenter Sangeeta Bhabra has been meeting the people who work and live in the castle to find out why the royal residence is so special.
The Queen is Head of State to sixteen Commonwealth nations, and the show has been designed to reflect all of these countries.
Musicians, dancers, choirs, actors - and the military - all playing a part in this unique celebration - as ITV Meridian presenter Fred Dinenage has been finding out.
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 Windsor Horse Show finally got underway today - but not without problems...or, in this case, mud!
Thousands of people were left disappointed when heavy rain meant yesterday's horse show - and rehearsals for the Queen's 90th birthday pageant on Sunday - were called off.
Ian Balding has trained thousands of horses over gallops in North Hampshire - many of them belonging to the Queen. He says that Her Majesty has 'natural horsemanship'.
A full list of events is taking place today in the Castle Arena, Frogmore Arena, Copper Horse Arena and Adelaide Arena.
The Queen's 90th birthday celebrations start tonight in the grounds of Windsor Castle in a purpose-built arena used by the Royal Windsor Horse Show during the day. It comes after events were rained off yesterday. Musicians, actors, dancers and the military will perform for 25,000 spectators over four nights with The Queen attending on Sunday.
Crowds have lined the streets of Oxford today - despite the rain - hoping to catch a glimpse of Prince William. The Duke of Cambridge was in the city to see three major investment projects at the University.
He began his day at the Weston Library where he spent a lot of time outside chatting to local schoolchildren about their favourite books. Kate Bunkall reports.
A preview performance of the Royal Windsor Horse Show has been cancelled. The event is part of the celebrations planned by the organisers of Her Majesty the Queen's 90th Birthday Celebrations in Windsor.
The organisers have said that the show in front of a live audience can not take place because of heavy rain. There will be no impact on performances for the rest of the week, but the organisers said that unfortunately they can not offer replacement tickets to anyone who was planning to attend tonight's show because all the other performances are sold out.
Nick Brooks-Ward, Director of Operations for the Royal Windsor Horse Show explains the situation below.