We hope you find this wheely interesting.
1. It wasn't London's first big wheel
The London Eye was preceded by The Great Wheel, a 40-car ferris wheel built for the Empire of India Exhibition at Earls Court.
The Great Wheel — modelled on the original Ferris Wheel from Chicago — opened to the public on 17 July 1895. It was 94 metres (308ft) tall and 82.3m (270ft) in diameter.
It ran until the Imperial Austrian Exhibition in 1906, by which time its 40 cars (each with a capacity of 40 people) had carried over 2.5 million passengers.
2. It's Europe's tallest 'ferris' wheel
When it was built in 1999, the 443ft (135m) tall wheel was the world's tallest.
But it's been pushed into fourth place, surpassed by the 520ft (158m) Star of Nanchang in 2006, the 541ft (165m) tall Singapore Flyer in 2008, and Las Vegas's 550ft (168m) High Roller, built in 2014.
The Eye is rather used be being toppled from first place: it used to be London's highest public viewing point too. The 804ft (245m) high observation deck on the 72nd floor of The Shard took away that accolade on 1 February 2013.
Marketing types like to refer to the Eye as the world's 'tallest cantilevered observation wheel' — a reference to the fact that, unlike a ferris wheel, it's supported by an A-frame on just one side, and the carriages don't hang below, they're outside the wheel rim and righted by motors.
3. It's very popular
With more than 3.75m visitors annually, The London Eye is the most popular paid tourist attraction in the UK.
(The British Museum holds the record for the most popular free attraction, welcoming more than 6m visitors each year.)
4. It was supposed to be temporary
Just like the Eiffel Tower, the London Eye was originally planned as a temporary structure; built to stand on Lambeth Council's ground on the banks of the Thames for around five years.
In July 2002, Lambeth Council granted the Eye a permanent licence.
Following a dispute between the Southbank Centre (which owns the land beneath one of the struts) and the London Eye, a 25-year lease was agreed on 8 February 2006. As part of the lease agreement, the London Eye provides the South Bank Centre (a publicly funded charity) with at least £500,000 a year.
5. It opened late
Built to celebrate the millennium, the London Eye only started carrying public passengers in March of that year.
The London Eye was formally opened by then prime minister Tony Blair on 31 December 1999.
It was due to open with various VIPs enjoying the views, but a clutch problem on one of the capsules meant it rotated without passengers, and the opening was postponed for a month.
The London Eye finally opened to the paying public in 9 March 2000.
6. It's part Skoda
The London Eye was dreamt up by a UK design team, but its parts come from all over Europe.
The wheel was developed and constructed in The Netherlands from UK steel, with cables from Italy, bearings from Germany, and the iron spindle and hub were cast in the Skoda factory in the Czech Republic.
The capsules were made by cable-car specialists Poma in the French Alps. And the double-curved laminated glass for the pods was made in Venice.
7. Unlucky number 13
The London Eye has 32 capsules, numbered 1 to 12 and 14 to 33. You can read more examples of London's triskaidekaphobic tendencies here.
The 32 capsules are said to represent London's 32 boroughs.
8. It's got one royal capsule
On 2 June 2013, a passenger capsule was named the Coronation Capsule to mark the 60th anniversary of the coronation of Queen Elizabeth II.
9. It's had a fair few monikers
Yes, the London Eye is also known as the Millennium Wheel.
But it's had many official names, courtesy of its various owners and sponsors. First, it was called the British Airways London Eye; then the Merlin Entertainments London Eye; then the EDF Energy London Eye.
In January 2015, it became the Coca-Cola London Eye, but sponsorship has since passed to lastminute.com.
10. Twinkly lights
The Eye is lit up in different colours to mark various special occasions.
For example, it was lit red, white and blue for Prince William and Kate Middleton’s wedding, and pink in 2005 to celebrate the legalising of gay civil partnerships.
The lights on the London Eye were changed for LED lighting in December 2006, allowing digital control of the lights and their colours.
11. Celebrities love it
If you like celeb-spotting in London, you might try and see who you can clock at the London Eye, because it seems celebs love it.
In 2016, Matt Damon made at least five trips; as did singer Meghan Trainor.
According to CN Traveler, Kate Moss has taken to the wheel a whopping 25 times; while at last count Jessica Alba has made a remarkable 31 trips on the Eye.