Thirty years ago today, on 6 October, 1985, East German athlete Marita Koch ran the 400m in a world record time of 47.6 seconds.
To put it into perspective, it was more than one and a half seconds quicker than American Allyson Felix clocked to take gold at this year's World Athletics Championships in Beijing.
Koch's record, set at the World Cup in Canberra, Australia, has been the subject of much debate in the intervening 30 years.
- No-one has come close to breaking it;
- And Koch competed in an era when East Germany was known to be systematically doping its athletes.
However, Koch, now 58, never failed a drugs test and has always maintained she did nothing wrong.
What does Koch say?
She does not give many interviews, but, at the end of 2014, she told BBC athletics reporter Ed Harry: "I don't have to prove anything to myself.
"I have a clear conscience. I can only repeat myself... I never tested positive, I never did anything which I should not have done at that time.
"I didn't achieve the world record out of nowhere. I had previously improved my time on five occasions, in slow steps, around the 48-second mark, and at some point it became a world record.
"Also, all world records are certainly in some way an exception, so now the next person has to come, or has to be born, who is ready to break the record. At some point, that time will come."
What do her critics say?
They urge us to read the evidence.
The state-sponsored, systematic doping of East German sportsmen and women was administered by the country's secret police, the Stasi.
On Germany's reunification in 1990, the Stasi's records were handed to a member of the German Science Council, Professor Werner Franke.
He subsequently made those records, detailing who was receiving banned substances and in what quantities, available to the public.
His wife, Brigitte Berendonk, also published a book in 1992 containing doping data for many East German athletes of the era, including Koch.
Following its publication, Koch threatened to sue but never did.
What's the IAAF's stance?
The data detailing dosages of banned substances that Professor Franke published has been used on numerous occasions over the last 25 years.
Specifically, it has helped former East German athletes claim compensation for medical conditions arising from their use of performance-enhancing drugs.
But the sport's world governing body has never used these figures to launch its own investigation.
It says it can't act because there is a 10-year statute of limitations in the World Anti-Doping Agency code, to which it adheres.
However, the IAAF told the BBC that "should an athlete subsequently admit to having used or taken advantage of a substance or a technique prohibited at the time", then it could act.
That could mean removing a record from the history books.
So what happens now?
Nothing, it appears. Some of Koch's former team-mates have asked for their performances to be removed from the record books.
As for Koch herself, she said she doesn't feel the need to continually defend her reputation.
"Everyone who knows me knows that I don't seek the publicity," she said. "If I am asked, then I answer. Aside from that, I just have to live with it."