When in the Middle Ages Pope Boniface VIII (1230-1303) repeated that "all roads lead to Rome", he invited pilgrims to stand on the left side of the road reinforcing a custom already prevalent among travelers and horsemen so to make better use of the sword in case of sudden attacks, writes the Italian magazine Focus.
In fact, archaeological finds show that in ancient times the great civilizations (Egyptians, ancient Greeks, Romans) stood on the left.
This custom was maintained in Europe until the end of the 11th century.
The reason was clear: most people were right-handed, and holding their left hand made it easier to draw their swords to defend themselves, ride horses, or walk sideways.
During the French Revolution, Robespierre ordered citizens to move to the right, in opposition to the Catholic Church.
A few years later Napoleon (who, among other things, was left-wing) exported this custom to the countries occupied by his armies, according to some even contrary to the custom in force in Great Britain.
Great Britain, in fact, always remained foreign to change and the territories of the empire inherited the same rules.
The earliest known written rule enforcing left-hand traffic in Great Britain was adopted in 1756 and concerned the London Bridge.
In the rest of Europe, some countries, for example the Scandinavian ones, continued to move to the left, while others were already traveling to the right.
In 1859 even the Japanese, then great admirers of British customs, decided to adapt to left-wing movements.
Meanwhile, the use of the right had spread to Europe.
The shift from left to right was almost complete between the late 1930s and 1940s, thanks to German rule by Adolf Hitler, who brought the nations of the former Austro-Hungarian Empire to the right.
The last European nations to side were Sweden in 1967 and Iceland.
Today, only about a quarter of the countries in the world move to the left.
In Europe only in Great Britain, Ireland and Malta.