It will be lit from the rays of the sun, but in common with all Youth Olympic flame ceremonies since 2012, it will take place not in Ancient Olympia but at the Panathinaiko Stadium in Athens.

The term "Olympic flame" has always been a sensitive issue and there have been calls for a new approach to how the is flame is presented from the Forum of Adriatic and Ionian Cities.

They are concerned that the use of "Olympic" style flames which do not originate in Olympia might "usurp the values, symbolisms and connotations of the Olympic flame".

The Paralympics, Asian Games, Pan American Games, European Games, Universiade and regional Youth Olympic festivals have all introduced the flame as part of their rituals. None of these are lit in Olympia.

Senior figures in the region, among them Konstantinos Antonopoulos, archaeologist for the area in which the Ancient Games were staged, have written to the International Olympic Committee (IOC) asking that they "pledge the termination of all ceremonies being held in places other than Ancient Olympia for obtaining a flame to be used for athletic meetings and festivals associated to Olympic institutions".

They believe that flames which are not lit in Olympia "create confusion and harm the uniqueness and authenticity of the cherished Olympic symbol".

So many Games now wish to use an Olympic-style flame as a symbol and the Forum have suggested an alternative for the "reinforcement of the authenticity" of the flame.

They would like to see an "eternally burning flame in its historically documented place, on a hearth in the Prytaneion in the archaeological site of Olympia".

An eternal flame does already burn at the Olympic Museum in Lausanne but they suggest it might burn not only at the IOC headquarters but every previous Olympic host city.

"The Olympic flame should also burn eternally, commemorating and celebrating the connection between antiquity and contemporary era, and demonstrating the relation of the different hosts of the Olympic Spirit," the Forum say.

"Thus, every sport event in the world implemented within the Olympic Movement could receive the original Olympic Flame from the nearest altar."

The idea of a readily accessible flame from Olympia around the world could allow any Games which enjoy Olympic recognition to use a flame with what is described as "original Olympic genes".

Nowadays there are many flames but in the early years even the ''Olympic fire'' did not always come from Olympia. Before 1936, the flame was fired with the flick of a switch and it was not until 1964 that the Winter Games flame was first kindled there and considered genuinely "Olympic".

It is unlikely there will be radical changes to the Olympic flame in the immediate future but since the first Youth Olympic Games, each Torch Relay has had a distinct character. Like previous youth flame ceremonies, those held next week in Athens for Buenos Aires 2018 are expected to closely resemble those held for the Olympic Games themselves. 

That should come as no surprise as the ceremonies are directed by Artemis Ignatiou, who choreographs the Olympic flame rituals.

The first Youth Olympic flame in 2010 was lit in Ancient Olympia by actress Ino Menegaki, as High Priestess. Then IOC President Jacques Rogge was present to see the flame kindled for Games which he personally had endorsed and the first bearer of the Torch was 15-year-old Greek trampolinist Apostolos Koutavas.

In what was called the "Journey of the Youth Olympic Flame", a city in each continent was chosen to receive the flame.

The first destination was Berlin where the flame travelled on the River Spree and was lit in a cauldron at the Brandenburg Gate.

"We are celebrating the future of sport," said future IOC President Thomas Bach at the time, who was part of the welcome party.

Then it was on to Dakar, Mexico City, Auckland and Seoul before arriving in 2010 host Singapore for a grand six day tour of the city state. The days typically began at a school or college and ended with a community celebration.

The bearers included Olympic champions Sasha Popov, Sergei Bubka and Yelena Isinbeyeva, as well as Sophia Pang, the first Singaporean woman to reach the south pole.

The final bearer was young sailor Darren Choy, who ran through a reflective pool to light a cauldron which resembled a lighthouse. This was appropriate for its water side location.

Organisers of the first Winter Youth Olympic Winter Games in Innsbruck made no secret of their decision to light the flame in Athens for "environmental and cost" reasons. In doing so they set a trend that has been followed by subsequent cities.

Although the 2014 Games in Nanjing were on a bigger scale than had previously been seen, the flame was lit at the Panathinaiko Stadium. The crowd included Greek President Karolos Papoulias who joined Honorary IOC President Rogge to watch proceedings along with hundreds of excited youngsters waving flags.

This time the first Torchbearer was fencer Marios Giakoumatos in an unusual pink and white uniform.

"Let the Youth Olympic Flame carry the passion and dreams of young people to every corner of the globe before settling in Nanjing," said Rogge, who thanked the Hellenic Olympic Committee "for allowing us to light the flame in Greece".

For the first time, a computerised app made it possible to carry a virtual flame. Staged over 108 days, it was an idea Nanjing had employed at the Asian Youth Games the previous year. Organisers claimed the virtual Torch Relay was warmly received by young people, who actively downloaded an app and shared the joy of passing on the flame to friends nearby. "By participating in the Torch Relay, they passed on Youth Olympic concepts around the globe," it was claimed.

Australia's double Olympic gold medal winning swimmer Susie O'Neill, who led the Australian team as Chef de Mission in Nanjing, said: "It is wonderful to let the whole world participate and break geographical and distance barriers, and the Virtual Torch Relay is a highlight in the Olympic Movement".

When the flame arrived in the Games city, it was lit after an Opening Ceremony which would have done credit to many Olympic Games. Diver Chen Ruolin, a double Olympic gold medallist in both Beijing and London, boarded a moving platform which carried her across the arena with an escort of runners to the main stage. 

There, a huge telescope transformed into five Olympic rings and the touch of the flame triggered a cavalcade of fireworks which exploded into the sky as the cauldron itself came to life.

When the Lillehammer 2016 Winter Youth Games opened, the flame burned first in the very cauldron which had been lit for the 1994 Olympic Winter Games.

The flame was then relocated to a futuristic but much smaller cauldron in the Sjogg Park in the centre of town.

Rio 2016 used the same idea to make the flame visible to as many people as possible.

When the flame touches down in Argentina next week it will not be the first time it has visited Buenos Aires. A decade ago the city was on the itinerary for the Beijing 2008 international Relay.

The original plan was for football icon Diego Maradona to begin the run, but Argentinian windsurfing medallist Carlos Espinola eventually took the flame.

Trouble had been expected. There were some demonstrations against the Chinese policy in Tibet, but the Relay was completed without anything like the disturbances seen in London, Paris and San Francisco. 

Tennis star Gabriela Sabatini, an Olympic silver medallist in 1988, was the final Torchbearer and the flame passed the obelisk on the Avenida 9 de Mayo. It is here that the 2018 Youth Olympic flame will complete its 14,000 kilometre journey, lasting 60 days.

The Relay proper begins on August 5 in La Plata and will also travel to Rosario, Santa Fe, Mendoza and Cordoba before the Opening Ceremony.

Once again social media users will be invited to carry their own digital flame under the hashtag #UnitedByTheFlame, part of an IOC campaign to promote the values of Olympism.