Weighing in at 65,000 tonnes with a length of 280 metres (918 feet), HMS Queen Elizabeth is the Royal Navy’s largest aircraft carrier.
The £3.1bn carrier and its sister ship HMS Prince of Wales are the most expensive in the Royal Navy’s history.
The total cost for both ships was first estimated at £3.5bn but was then revised and almost doubled to £6.2bn.
It has a crew of 700 and 155,000 miles of electrical cables inside.
Today, the Queen was one of the first to board her namesake warship in Portsmouth to see the Royal Navy White Ensign raised on the vessel for the first time.
Alongside was Princess Anne, Prime Minister Theresa May and First Sea Lord Admiral Sir Philip Jones.
Today’s ceremony saw the Queen commission the boat to be officially handed over to the military.
About 3,700 guests attended the event, which comes more than three years after the ship’s official naming ceremony in Rosyth.
It took eight years to build HMS Queen Elizabeth, with construction taking place in six cities and involving 10,000 people.
Until now, the ship has been flying the Blue Ensign but once it’s been formally given to the Navy it will raise the new flag.
Capt Jerry Kyd said the ceremony was the ‘culmination of a number of years of real excitement.’
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He said: ‘The first sailing from Rosyth was only nine months ago, we have come a long way.
‘The first entry into Portsmouth was in the summer and here we are today accepting the ship into Her Majesty’s fleet formally.
‘So, it is right at the top, it is the latest milestone, many more to come, but hugely exciting and a very proud day.’
HMS Queen Elizabeth successfully completed her sea trials but will not begin flight trials until 2018.
She spent a month at sea travelling around the south-west of the United Kingdom testing out the radar, communications and other technical equipment.
It’s thought the first proper deployment with jets on board won’t happen until 2021.
Although she has the potential to carry 36 F35 jets, the reality is set to be far less, with each jet costing around £100m.
The warship has an estimated lifespan of 50 years and in this time could be used for high intensity war fighting or providing humanitarian aid and disaster relief anywhere in the world.
A spokeswoman from the Aircraft Carrier Alliance said: ‘This is really fantastic day. It’s the culminates years of hard work and dedication of 10,000 people across the UK and wider supply chain.
‘For the industry we have made history this morning.’