Tourists queue outside the Pyramid prior entering the Louvre museum in Paris on July 19, 2019. (AFP/Alain Jocard)
Like a human wave every few minutes, two hundred or so tourists surge towards the "Mona Lisa", mobile phones in hand to make the best of every second of their time in front of the world's most famous painting.
Hundreds of other hearts sink as museum attendants swiftly draw the rope across to hold back the next wave of the queue that snakes round the vast gallery in the Louvre in Paris.
Nobody seems to notice the superb Rubens that line the walls of this monumental corner of the Richelieu wing -- everyone is focused on the end of the queue and their big selfie moment.
The queing begins several hundred meters away under the museum's glass pyramid where tourists join the first of a series of staggered lines that will slowly lead them to their brief audience with Leonardo Di Vinci's masterpiece.
Last month, officials had to restrict access to the world's most visited museum for three days because of the chaos caused by queues to see the "Mona Lisa" in her new temporary home in the Medici gallery.
Blockbuster Leonardo show
She will be returned to her traditional spot in the adjoining States Room -- which is being refurbished -- just before a blockbuster Leonardo exhibition opens at the Louvre in October.
But the disruption -- exacerbated by an influx of tourists escaping the fierce heat in the French capital in July -- has pushed the Louvre to introduce obligatory advance booking by the end of the year to try to control numbers.
Already angry staff closed the museum for a day in May to protest about being overwhelmed by the spiraling numbers.
More than 10 million people visited the museum in 2018, with that record likely to be smashed again this year.
With between 75 and 80 percent of them -- particularly Chinese and Americans -- coming to see the "Mona Lisa", the museum's vice managing director Vincent Pomarede insisted that booking a time slot was now essential.
"A tourist who comes without a reservation runs the risk of waiting a long time and maybe even not getting in," he told AFP.
"It's the only way to guarantee entry."
Pomarede said many other major museums already require people to book ahead.
"Before the end of the year, all visitors will have to make reservations," he said.
For Evelyn and Tai, tourists from Jakarta and Kuala Lumpur, advanced booking made seeing the "Mona Lisa" "fairly painless".
"The line is pretty long... but we bought the ticket online so we got a designated time."
"It is much better organized than when I last came in 2000," said Stan, a Taiwanese-American visitor from San Jose in California.
Finally seeing the painting was "pretty cool", said his 17-year-old son Andy, though he "wasn't blown away by it".
New Yorkers Frank and Jennifer, however, thought the whole experience was "amazing".
"It's beautiful... and better than I expected I was expecting a really old building but it's a really modern (setting) for old artifacts and art," Frank added.
Visitors numbers usually peak at the Louvre at Easter.
But this year they have continued to soar over the summer, with government advice to seek shelter in air-conditioned spaces like museums during two record heatwaves in the French capital further complicating matters.
With queues worst in the peak early afternoon period, Pomarede is worried that the 30,000 people who pass in front of the "Mona Lisa" daily will stop visitors seeing some of Louvre's many other treasures such as the Venus de Milo, the Winged Victory of Samothrace, and its staggering collection of 18th- and 19th-century French art.
Until the "Mona Lisa" returns to her home in her more controllable side gallery, "we are promoting other itineraries for visitors to see other work by Leonardo, as well as our Egyptian, Greek and Roman antiquities," he added.
In the meantime, the Louvre has borrowed some tricks from the French capital's road traffic management system, including screens at the entrance warning that the museum is full or crowded, as well as warning on its website.