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.
The Queen's love of horses is well documented and that passion is reflected in the celebrations over the next few nights.
As a young princess she enjoyed riding in Windsor Great Park - something she still does today.
The Queen owns and breeds thoroughbreds. Those close to her say horse racing is when she really relaxes. Penny Silvester has been talking to the Queen's Racing Advisor, John Warren, about why her affection for these animals runs so deep.
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.