What you need to know:
- Tutu, who died on Sunday aged 90, had largely faded from public life in recent years but was remembered for his easy humour and characteristic smile -- and above all his fight against injustices of all colours.
- South Africa's President Cyril Ramaphosa called him a man of "extraordinary intellect, integrity and invincibility against the forces of apartheid".
- Tutu was diagnosed with prostate cancer in 1997 and repeatedly underwent treatment.
South Africans of all races stopped by Cape Town's St George's Cathedral on Sunday to pay their respects to Archbishop Desmond Tutu, the anti-apartheid icon who has died aged 90.
"His significance supersedes the boundaries of being an Anglican," said mourner Brent Goliath, who broke down in tears outside the old stone building.
He told AFP he had been an altar boy and had met Tutu several times.
"I was very emotional this morning when I heard that he'd passed away. I thank God that he has been there for us," he said, wiping his eyes as he placed a bouquet of pink flowers under Tutu's photo.
In the cathedral yard, Father Michael Weeder, dean of the cathedral, paced up and down answering phone calls and speaking with workers shortly after Sunday morning mass.
"He died a holy death," he told AFP near a makeshift shrine being prepared for the public to leave flowers.
Despite the loss, he said "it comes with some relief to the family because Father Desmond has been in a lot of pain over these past weeks".
Members of Tutu's family could be seen gathering and embracing each other in his former Cape Town residence behind a police security cordon.
'He fought for us'
Dozens of South Africans stopped at the cathedral, even though many people would not yet have heard of his death -- it is customary to switch off and spend the day after Christmas on the beach, rather than pacing the city.
Among those paying respects was Miriam Mokwadi, a 67-year-old retired nurse, who said the Nobel laureate "was a hero to us, he fought for us".
"We are liberated due to him. If it was not for him, probably we would have been lost as a country. He was just good," said Mokwadi, clutching the hand of her granddaughter.
Daphney Ramakgopa, 58, a local government worker, spoke of the loss the entire country was feeling.
"We looked up to him as the adviser to everyone in the country, especially our politicians," she said.
Many passers-by remembered Tutu not just for his role in the fight against apartheid, but for how he has continued to hold the democratic government to account, constantly calling out corruption in the ruling African National Congress party.
"I can't think of anybody with that kind of moral compass" left in South Africa, said Aki Khan, a 64-year-old sound engineer and veteran of the apartheid struggle.
"But I really do think his message has filtered through to young people."
Cape Town's famous Table Mountain is due to be lit up in purple from 2000 GMT until the funeral on January 1.
"Knowing he had been ill for some time has done little to lessen the blow dealt to South Africa this sad day," President Cyril Ramaphosa said in a televised address.
"He was a man of unwavering courage, of principled conviction," he added, announcing flags would be flown at half-mast nationwide until the evening before the funeral.
'Won't forget this man'
In the township of Soweto near Johannesburg, which became synonymous with apartheid-era repression, youngsters took selfies outside Tutu's former home, just a few metres from Nelson Mandela's house.
Local resident Lerato remembered Tutu jogging around the surrounding streets in the morning and called his death "a big blow".
"This street is the only one in the world in which two Nobel Peace Prize winners have lived. You can then imagine us, the neighbours around, we are really touched by his passing," she said.
Another resident, Samba, recalled seeing Tutu when he came to have a drink. "He was a down-to-earth person. It was great. I won't forget this man," he said.
"His legacy will be his love for all people. He always said that God is not the God of Christians, but God is God of all people," added Stephen Moreo, the Anglican bishop of Johannesburg.