The sleepy town of Amboise on the Loire River — where Leonardo died in 1519 at the age of 67 — was in virtual lockdown because of fears of protests by France's grassroots “yellow vest” movement.
Traffic in the town of just 13,000 was banned within a five-kilometre radius and the usually teeming restaurants and shops shuttered.
Italian president Sergio Mattarella with his daughter Laura and French president Emmanuel Macron with his wife Brigitte
On Wednesday, dozens of cars were towed away, with some foreign owners apparently unaware of the draconian security measures.
The presidential helicopter had arrived on a river island in the heart of the town, touching down on a pad usually used to launch hot-air balloons over the chateau-studded valley.
After the visit to Leonardo's grave, Macron and Mattarella headed for lunch at the nearby Clos Luce, the sumptuous manor house where Leonardo lived and died under the patronage of King Francis I.
Later they planned to visit the sprawling chateau of Chambord – whose central double-helix staircase is attributed to Leonardo though the first stone was not laid until four months after his death.
The two presidents lay flowers at Leonardo Da Vinci's tomb
Among glitterati attending the events will be Italian star architect Renzo Piano and French astronaut Thomas Pesquet.
The joint celebrations come after months of mounting diplomatic tensions between Paris and Rome over the hardline policies of Italy's populist
government and its support for France's anti-government “yellow vest” protesters.
In the worst diplomatic crisis between the two countries since World War II, Paris briefly recalled its ambassador from Rome.
Mattarella, staunchly pro-EU like Macron, played an “essential role” in lowering tensions, Macron's office said.
Laura and Brigitte pay their respects
Francis I, known as the “Sun King of the 16th century”, is widely credited with bringing the Renaissance to France, even if his predecessor Louis XII had begun the process by bringing in architects and artisans from Florence, Milan and Rome.
Leonardo was 64 when he accepted the young Francis I's invitation to Amboise, at a time when rivals Michelangelo and Raphael were rising stars.
With Leonardo's commissions drying up, it came as a great relief and no small vindication for the Tuscan artist, who received a handsome stipend as the “first painter, engineer and architect of the king”.
At the time, Francis I was barely 23, and his ambitious mother Louise of Savoy “knew that Leonardo would be the man who would allow her son to
flourish”, Catherine Simon Marion, managing director of the Clos Luce, told AFP.
Macron greets the Count of Paris and his daughter Princess Antoinette
Leonardo brought with him three of his favourite paintings: the Mona Lisa, the Virgin and Child with Saint Anne, and Saint John the Baptist — all of
which today hang in the Louvre museum in Paris.
Macron is the first French president to visit the town since Charles de Gaulle came in 1959.
A replica of the mechanical lion attributed to Da Vinci is displayed at Amboise
Emmanuel Honnet, who runs the Cafe des Arts snack bar by the chateau, said the precautions were “understandable… given the terrible social climate and the real terrorist risk”.
But the 51-year-old vented “frustration” that the townspeople were largely sidelined. “It should be the memory of a lifetime,” he said.