Next week's San Marino Grand Prix will be one of remembrance as Formula One returns, possibly for the last time, to the Italian circuit.
Imola 1994 was a watershed for grand prix racing, shocking the world and robbing the sport of a three-times world champion still considered by many to be the greatest man who ever graced a racetrack.
"He was the one driver so perfect that nobody thought anything could happen to him," said former McLaren team mate Gerhard Berger after a terrible weekend that also claimed the life of Austrian Roland Ratzenberger.
"He was the only driver I respected," declared four-times champion and old rival Alain Prost.
The painful memories, present every year at Imola, will remain even if the circuit has changed and teams treat next week's race, coming a week before the May 1 anniversary, as business as usual.
"I'll try and keep my head low, as will Patrick," said Frank Williams, the team boss who faces yet another trial in Italy along with technical director Patrick Head and former designer Adrian Newey as a result of Senna's death in their car. "It's a sad event but we won't be reminded of it too overtly."
BIG DEBATE
All will remember a hugely talented driver and may wonder, as many have over the last decade, what might have happened had Senna lived.
Would Ferrari's six-times world champion Michael Schumacher, now heading for his fourth win in a row to match the best start of his career in 1994, have been the same record-breaking phenomenon that he is today?
One can only imagine the battles the two might have had. Senna was 34 and at the height of his powers just as the 25-year-old Schumacher was emerging with Benetton.
Could Senna, whose record of 65 pole positions still stands, have equalled Juan Manuel Fangio's record of five titles before Schumacher did in 2002?
Their rivalry might even have matched the intensity of that between Senna and Prost, a feud fuelled by hugely controversial title-deciding collisions at Suzuka in 1989 and 1990.
"He felt that there was a part of Formula One that was prepared to win at all costs," said McLaren boss Ron Dennis, whose cars took Senna to his titles, when asked what the Brazilian had thought of Schumacher.
"It was a group of people that fell into that category, not just drivers, but elements of teams or whole teams. And he felt that certainly Michael fell into that category and that was never his way of going into Formula One."
Whatever the conjecture, it only heightens the mystique of an absent champion whose charisma, intelligence and talent combined the spiritual and the sporting to a rare degree.
TREMENDOUS INTEREST
Dennis spent more than an hour talking to reporters about Senna at the last Bahrain Grand Prix, just as the Brazilian had kept them spellbound in the past.
"His legacy is moments like this," said the team boss. "Even 10 years after he lost his life there is still a tremendous interest in him as a person.
"I do not think Ayrton would change anything that happened," he added. "He lost his life doing something he was passionate about and it was his life to the exclusion of many things that other drivers and individuals enjoy."
Dennis said Senna knew the risks he was taking and would also have known when to quit, drawn as he was by the pull of Brazil.
"He was never going to have a career (in F1) beyond being a driver. He was disinterested. He didn't particularly like the environment of grand prix racing from a non-driving standpoint.
"He would most certainly have used his influence and his fame to help the underdogs of Brazil, those people living in the favelas (slums) and the children," said Dennis
The Senna Foundation, run by the late driver's sister Viviane and former associates, has done just that to help tens of thousands of street children.
That is a part of his legacy but there are others, not least the big improvement in safety as a result of his terrible crash at the Tamburello corner.
The Brazilian introduced a new intensity to the sport. He was unforgettable in qualifying with a look of utter concentration and commitment in his eyes before the visor came down.
He was dominant in Monaco, winning a record six times in the principality, while his performance in the wet to win the 1993 European Grand Prix at Donington Park ranks high on most people's lists of best ever races.
And as a champion, his influence on others was profound -- even if some of his tactics were dubious.
"Senna was able to change the mood and style of the sport, with consequences that outlived him," wrote Richard Williams in his 1995 book 'The Death of Ayrton Senna.'
"As the best of his time he became, for good or ill, the example for ambitious young drivers to follow".
