Hundreds of people mourned the death of Lee Hee-ho, the wife of the late former President Kim Dae-jung, on Tuesday.
A five-day public funeral service is being held for Lee and a memorial altar has been set up at Yonsei Severance Hospital in Seoul.
Lee, who had been battling liver cancer, died late Monday at the age of 97.
Prominent figures, including Prime Minister Lee Nak-yon and National Assembly Speaker Moon Hee-sang as well as ruling and opposition party lawmakers paid their respects.
Top presidential aides also visited, relaying President Moon Jae-in's condolences.
South Korean citizens also came to pay tribute and remember the former first lady.
"I wonder how we will fill her absence as the mother of our country, and as a pioneer of democracy. She suffered and overcame all sorts of hardships for her husband to eventually become the president."
"I decided to visit because I felt empty hearing the news. It's really a shame to lose someone who devoted her whole life to democracy. I hope she rests in peace."
Lee, born in 1921, studied at South Korea's prestigious Seoul National University, as well as in the U.S at a time when many women in the country had limited access to education.
During her life, Lee spared no efforts to improving women's rights and promoting inter-Korean reconciliation and democracy.
She was also a supportive companion to former President Kim.
In her will, Lee wrote that she would pray for the Korean people and a peaceful unification of the two Koreas in heaven.
"She thanked the people for their love for her husband, former president Kim Dae-jung, and herself. She added that she hopes the people love and find harmony with one another and live happy lives. And that she will pray for the Korean people and for peaceful unification."
At the request of the funeral organizers, the South Korean government also informed North Korea of Lee's death.
Eyes are on whether Pyeongyang sends a delegation to pay tribute, as it has done in the past for figures who contributed to inter-Korean relations.
"Many more are expected to come and pay their respects to the former first lady over the next few days. Lee will be buried on Friday at the Seoul National Cemetery, where her husband was laid to rest a decade ago. Kim Min-ji, Arirang News."