On a busy Sunday morning in the middle of Paris, a brazen and remarkably efficient plan to steal some of the French crown jewels was put into motion.
Within just a few minutes, some of the priceless historical treasures had been removed from their gilded gallery home and were disappearing down a French highway on the back of Yamaha scooters, potentially lost forever.
Now, as French authorities scour Europe for some of their nation's most prized possessions, closer inspection of the Louvre museum itself reveals just how vulnerable it was to this type of attack.
Breaching the Louvre
While popular culture might depict the Louvre museum as one of the most secure buildings in the world, stepping through key details of the heist reveals the factors that led to thieves using notably unsophisticated means to escape with some of its exhibits.
The Louvre museum boasts layers of security including alarms on exhibits as well as a long list of restrictions for the millions of visitors who walk its halls each year.
Visitors are swept for tools that could do damage or aid a robbery and larger bags must be left behind in lockers.
But when the heist occurred, the museum had just opened and experts say, this can be a vulnerable time of day.
"Lots of objects have been stolen during the day. You are distracted, all of those security guards are distracted by thousands of people coming into the museum, particularly as it had just opened," said Donna Brett, associate professor in art history at the University of Sydney.
Those entering the Louvre museum are not allowed to bring in screwdrivers, pliers, wrenches, hammers or clippers.
While tourists making their way into the museum were being screened for such implements, thieves were using a crane and power tools to let themselves in via a window.
The window in question is located on the south side of the museum, facing the River Seine.
The Louvre museum has three wings and five levels. The Apollo Gallery that was targeted by the thieves sits on level one at the start of the Denon wing and runs adjacent to the street.
The window used by the thieves is at the southern end of the gallery above a busy road and a section of wide footpath where vehicles could feasibly park and not look out of place.
On Sunday morning, local time, parked underneath the window was a truck-mounted lift and ladder.
Officials say the intruders brought the vehicle to the site, parking it on Quai Francois Mitterrand, one of the roads that run the length of the museum.
At 9:30am, local time, just half an hour after the museum opened, the thieves used the lift or ladder to reach the first floor balcony off the Apollo Gallery and began to force their way in.
They used a disc cutter to cut panes on the gallery's window, before at least one of the reported four intruders gained access to the exhibits, according to French officials and verified video of the incident.
In doing so, these thieves moved from a street with public access directly into the room housing the French crown jewels in a matter of minutes.
French officials said there were four intruders wearing balaclavas, and at least one wearing a high-vis construction-style vest involved in the heist, and that while they were not armed, they did threaten guards with angle grinders.
Staff had been warning about vulnerabilities at the Louvre. Their unions say tourism leaves too few eyes on too many rooms and creates points where construction zones, freight routes and visitor flows meet.
On Sunday, local time, a set of circumstances occurred that meant a piece of heavy machinery parked up against the museum did not raise any alarm before it was too late.
Officials were quick to suggest there had been security upgrades to the museum, including new-generation cameras, perimeter detection, and a new security control room, but reporting since has revealed delays in improvements, including that just a quarter of one wing of the museum is covered by video surveillance.
Speaking on French radio, Interior Minister Laurent Nuñez said "there is a great vulnerability in French museums" but insisted security had been strengthened.
"There are ticket checks, pat-downs, there are security guards in every room, so security has obviously been reinforced," he said before being asked if the problem then was that the building's security was lacking in regards to its exterior.
"They came in through the outside. You can't stop everything. That's how it is. It's very complicated," he said.
The French government has since ordered a security review at the Louvre as well as checks at other cultural sites across the country.
The Louvre dates back to the 12th century, but much of the original medieval fortress was razed and replaced with a royal palace in the 1500s. King Louis XIV would move from Louvre Palace to Versailles the following century.
The structure that is now considered the busiest museum in the world was "never designed to accommodate the millions of visitors it now receives each year", according to Lynda Albertson, chief of the Association for Research into Crimes against Art (ARCA), an organisation that examines and tracks trends in museum security including theft and vandalism.
She said the Louvre's architecture was not built "to address modern security needs, rigorous conservation controls, or the massive crowds it now attracts".
"These factors create a perfect storm of inherent vulnerabilities that purpose-built modern museums may not face."
Entering the Apollo Gallery
Inside the Apollo Gallery antiques and artistry from centuries past drip from the walls and ceiling and sit within the cabinets meant to keep them safe.
The room was designed to be King Louis XIV's reception hall and royal gallery.
It's decorated by some of the greatest artists in French history including Le Brun, Girardon, Lagrenee and Delacroix, and served as a model for the Hall of Mirrors at the Château de Versailles, according to the museum.
King Louis XIV identified with the god of the sun Apollo, and this gallery was to be made in that image.
This gallery sits just a few hundred metres from perhaps the biggest tourist attraction on the French cultural circuit, Leonardo da Vinci's Mona Lisa — once the subject of an elaborate heist herself.
The Apollo Gallery houses 105 artworks, according to a statement issued by the museum when the gallery reopened in 2020.
In the centre of the room are three glass cabinets that hold the crown jewels.
The Apollo Gallery measures 61.34 metres long and 15m high, according to museum material.
The intruders entered from the south side, crossed the floor to the centre of the room and approached the glass cabinets.
The cabinet closest to the window through which the thieves entered the gallery held some of the treasures from the House of Bonaparte, in particular the last known remaining pieces of Empress Eugénie's jewellery sets.
The central cabinet contained pieces set with sapphires and emeralds that once belonged to Queen Marie-Amélie, Queen Hortense and Empress Marie Louise, a wife of Napoleon I.
It is in these glass cabinets where the the crown diamonds — the Regent, the Sancy and the Hortensia — are also typically held.
The French crown jewel collection was first assembled in the 1500s, but it was passed from monarch to monarch, altered for different tastes, grew in size before being dispersed during the French revolution.
It was Napoleon I who again brought a crown jewel collection together before the French state decided to sell it off in 1887.
According to the Louvre, since then, the museum "has made every effort to recover these artworks, acquiring the prestigious items for the Department of Decorative Arts whenever the opportunity has arisen".
Daniela Mascetti worked for Sotheby's for 40 years, including as its European chief of jewellery and personally handled some of the pieces that were stolen as they made their way to auctions and back to France.
She said the Society of Friends of the Louvre, a group of philanthropists and enthusiasts, was sometimes chipping in for high-valued items that appear on the open market to reunite jewels of national significance.
"These are jewels that the French state had decided to alienate in 1887. [The society helps] bring them back to the state and give them to the public to admire and they just went like that. It's an ironic situation," she said.
"The state decides to sell them, the private [actor] decides to give them back to the state and they disappear again."
In 2020, the jewels that make up the modern crown collection were put on display together. In total, there are 23 pieces in the collection in the Apollo Gallery, according to the Associated Press.
After entering the gallery through the window on the riverfront facade, the intruders reportedly headed straight for the collection.
A video from inside the gallery, which ABC News has independently verified, shows a person in a high-vis vest standing at one of the three glass cabinets housing the jewellery.
The Associated Press is reporting alarms brought security personnel to the room, but as easily as they had entered the gallery, the intruders left, albeit now carrying a fortune.
What they stole
It appears as if the thieves attempted to steal nine pieces from the crown collection, but they dropped one on the way out and left an earring behind.
Among the pieces now missing are three items that once belonged to Empress Eugénie, Napoleon III's wife — a corsage-bow brooch, a diadem, or tiara, and a reliquary brooch. Eugénie's emerald-set imperial crown, which is reported to contain more than 1,300 diamonds, was found outside the museum. Officials said it had been damaged.
Also stolen, was an emerald necklace and earrings from the matching set of Empress Marie-Louise, Napoleon Bonaparte's second wife.
As well as a sapphire tiara, necklace and a single earring from a matching set linked to queens Marie-Amélie and Hortense.
A price can't be put on these treasures, but French President Emmanuel Macron said the theft was "an attack on a heritage that we cherish because it is our history".
Justice Minister Gerard Darmanin said in an interview on French radio: "There are many museums in Paris, many museums in France, with priceless values ??in these museums."
"What is certain is that we failed," he said.
In the late 1800s, when the French state sold off the crown jewels collection, it retained the 'Regent' diamond — a stone so valuable that it was at times used to guarantee France's foreign loans.
Sotheby's now estimates its value to be in the realm of $US60 million.
It's worth noting the Regent diamond has been stolen several times since being mined in 18th century India, but in this heist, it was spared.
Assessing the damage, Paris Prosecutor Laure Beccuau said on French television she did not know why the Regent diamond was not taken.
"I don't have an explanation," she said.
"It'll only be when they're in custody and face investigators that we'll know what type of order they had and why they didn't target that window."
Hinting at motive, Ms Beccuau appears to be suggesting the thieves were working to an order.
Dr Brett said it was apparent the thieves got "exactly what they were after".
"There are lots of different reasons why someone might steal material like this. It could be a targeted theft for someone who wants the jewellery. It could often in these types of scenarios and — it happened with the Munch for instance that was stolen in Norway years ago — they are actually then used for collateral for drug deals, all sorts of other kinds of international reasons," she said.
"They might break it up. I doubt whether they'll be able to sell them as they are right now because the first thing that will happen is that the police will put it onto Interpol."
Whether or not this was a robbery to order, there was one item that made it out of the museum, but was left behind — Empress Eugénie's crown now becomes a clue.
The getaway
It remains to be seen how long this heist took to plan, but its execution was over in mere minutes.
Estimates put the time between cutting open the south-facing window to fleeing on the Yamaha scooters between four and seven minutes.
French media is reporting the four intruders climbed onto two Yamaha scooters and made their getaway.
French authorities say they know which direction these scooters were travelling, but there has been no update on the search.
The investigation will involve a specialised police unit that, the French government says, has a high success rate in cracking high-profile robberies, but art theft commentators fear these items will never be seen again.
At the same time as law enforcement pursues those who committed this brazen robbery, there are a myriad of questions about those who let it happen.
Louvre employee and general secretary of the Sud Culture Union Elise Muller said there was dysfunction inside the organisation.
"Alerts have been issued for months and months by all safety and security personnel, in particular to highlight the flaws and problems we were facing daily and in fact, management completely ignored all these alerts, and today, what we feared happened: looting and pillaging," she said.
"We had identified a number of weaknesses, and it turns out that this identification is now clearly not only internal. But the weakness of the Louvre and its inability to fulfil its primary mission are known externally. And today, it is known to the entire world."
The Louvre Museum told the ABC it would not comment on these matters.
