There’ll be performances from actors, musicians, bands, dancers and the military and the event has been designed to reflect The Queen’s love of horses, her connections with the Armed Forces and the Commonwealth.
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.
Monday's weather forecast
Philippa has the outlook for the week ahead
A vigil has been held to remember the three victims of the terror attack in Reading.