Video report by ITV News Correspondent Carl Dinnen in Havana
Before the sun rose, Cubans began queuing around Havana's Revolution Square to pay their respects to former President Fidel Castro, the communist guerrilla leader who led a revolution in 1959 and ruled the Caribbean island for half a century.
Castro died on Friday at the age of 90, a decade after stepping down due to poor health and ceding power to his brother Raul.
Castro was cremated on Saturday and at 9am on Monday a 21-gun salute marked the start of a nine-day period of mourning.
People were expecting to walk past his ashes, but his family requested that they should not be moved to the Square until Tuesday's memorial service.
So instead thousands of Cubans filed past a photograph of Castro and a display of his medals, and afterwards many of them were visibly overcome with emotion.
One elderly man told ITV News that he had learnt a lot from Castro's rule.
He said: "He changed my life. I've learned a lot from him. Not to live only for money, that's what he teaches us, that we can help others."
Castro's cremated ashes will be laid to rest in the birthplace of the revolution when the mourning period ends on December 4 at Santiago de Cuba, the city in eastern Cuba where he launched his movement.
While many leaders in the region will attend the commemoration mass and funeral some others have said they will stay away.
Castro is a polarising figure who was seen as a hero by some but who has been condemned by critics, including US President-elect Donald Trump, who called him "a brutal dictator who oppressed his own people."