Ayrton Senna & Roland Ratzenberger lost their lives 27 years ago, with both drivers succumbing to injuries sustained in separate crashes during qualifying and the race at the 1994 San Marino Grand Prix.
Ratzenberger, taking part in just his third Grand Prix weekend, was killed when the front wing of his Simtek failed approaching the Villeneuve corner during qualifying.
Senna lost his life after spearing into the barriers at Tamburello while leading the race in his Williams. His crash has never been conclusively explained, but is believed to have been caused by a failure of some sort, or possibly some debris from a startline crash.
Formula 1 has kept Senna and Ratzenberger to the forefront of their thoughts this weekend in Portugal, marking 27 years since that black weekend at Imola.
Many of the teams, drivers and media personnel who raced against and with both men paid tribute to them, as you can see below.