Austrian President Alexander Van der Bellen, Arnold Schwarzenegger and several Formula One stars were expected to attend the funeral.
ADVERTISEMENTFamily, friends and fans have gathered on Wednesday at St Stephen's Cathedral in Vienna for a final farewell to Formula One legend Niki Lauda.
The coffin of the three-time champion was decorated with his red racing helmet. Before the service, hundreds of fans solemnly walked by the coffin, many taking photos on smartphones.
"I am so proud of Niki. He is a great Austrian, he achieved [so] much. I'm very sorry and I really felt obliged to accompany him on his last journey and be here," said Jenny Piffel, a fan from Vienna.
"He was simply a great human being and especially a great Austrian. He never gave up and that was very important in his life," said Leonie Schwalb, another mourner from Vienna.
Lauda died aged 70 last Monday, less than a year after undergoing a lung transplant.
The Austrian, who won two of his Formula One titles after a horrific crash in which he suffered serious burns, later became a prominent figure in the aviation industry and in recent years served as a non-executive chairman of the Mercedes F1 team.
Austrian President Alexander Van der Bellen, Arnold Schwarzenegger and several Formula One stars were expected to attend the service.