While Queen Elizabeth II is still looking a picture of health, pictured recently out and about the Royal Windsor Cup in Surrey, at 92 she is the longest-reigning monarch in the UK's history.
During her reign, she has seen the rise of the Commonwealth, the passing of the British Empire and seen 13 (and counting) Prime Ministers pass through Downing Street.
While we hope it doesn't happen anytime soon, it is inevitable that one day our Queen's ruling will end and the crown will be passed on.
From changes to the national anthem, stock market woes and a suspension of comedy shows, here are some of the things we can expect when the Queen dies...
Firstly, the whole of the UK will go into an official 12-day period of national mourning. Union Jacks will be flown at half mast throughout the country and books of condolence will be opened at embassies across the world.
The London Stock Exchange will be closed for at least the day of the Queen's funeral and potentially for several days - potentially costing the economy billions.
The Queen’s body will be taken to Parliament, where she will lie in state in Westminster Hall – like the Queen Mother in 2002 – until her funeral.
More than 200,000 people travelled to pay their respects to the Queen Mother and that number is expected to be vastly exceeded in the event of the Queen's death.
The BBC will be the ringleader in announcing the what-will-be devestating news. If Her Majesty dies during the night, her death would reportedly not be announced until 8am, after which her portrait will be displayed on the screen accompanied by the national anthem - as happened following the death of Princess Diana in 1997.
Other channels are not required to interrupt regular scheduling, but almost certainly will.
The BBC will also suspend all comedy programming during the 12-day period of national mourning.
As the throne is technically never vacant, as soon as the Queen passes, Prince Charles will automatically become King.
However, the accession council would need to be convened at St James’s Palace to formally declare Charles the king.
He would be asked to swear loyalty to Parliament and the Church of England in front of the council.
In turn, the Houses of Parliament will be recalled to swear loyalty to him.
The words to the National Anthem will be changed and new postage stamps and currency created to reflect Prince Charles’ ascension to the throne.
The only way Prince William would become king is if Prince Charles chooses to abdicate and pass the throne to him.
The Queen's state funeral will be the biggest ever seen in the UK - far eclipsing the likes of Princess Diana, the Queen Mother and Margaret Thatcher.
The service will be led by the Archbishop of Canterbury, currently the Rev Justin Welby.
Politicians and heads of state from across the globe will attend as well as the Royal Family.
As such, the event is likely to be one of the most heavily-protected of all time, with armed forces drafted in to guard against potential terror attacks.
Her coffin will be taken from Westminster Hall and travel through crowds of thousands of mourners by gun carriage to Westminster Abbey for the service.
It is expected the Queen will be interred in St George's Chapel at Windsor Castle, where her mother and father, King George VI, are buried.
Parts of this article originally featured in Mirror.