(CNN) William Helmreich, a prominent sociologist perhaps best known for walking every block of New York City, died Saturday morning of coronavirus, his family said.

He was 74.

Helmreich wrote nearly 20 books, including "The New York Nobody Knows: Walking 6,000 Miles in the City," which chronicled his walks through New York City talking to and learning about its residents.

Born in Switzerland to Holocaust survivors, Helmreich immigrated to New York City as an infant, eventually becoming a sociology professor at the City College of New York.

"Professor Helmreich was a true City College institution, a man with a restless curiosity about the people around him, a ceaseless investigator and an avid storyteller," CCNY President Vincent Boudreau said in a statement to CNN.

Helmreich prided himself on having walked every block of the city, earning an everyman's view of daily life.

"He believed that everybody had a story worth telling," Jeffrey Helmreich said of his father. "Every place and every person was interesting to my father. And every person felt interesting when talking to my father."

Helmreich, who also wrote spinoff volumes highlighting each of the city's boroughs, was working on the final entry in his series before he died.

"He was just about to finish Staten Island," his son said. "We've still got to finish that one."

Highly regarded in academia, Helmreich also reveled in the joy and grittiness of everyday life, his family told CNN.

"He was so intensely human as a scholar. It was so much about learning with his feet, with his heart, with his intuition, with his gut," said Jeffrey Helmreich, who is a professor at the University of California, Irvine. "He talked his way into everyone's hearts and revealed it to the rest of us."

After testing positive for coronavirus, Helmreich's symptoms appeared to be improving when he died suddenly on Saturday.

"We weren't ready for this at all. We didn't say goodbye. We didn't think we had to say goodbye," Jeffrey Helmreich said.

His family held a virtual funeral, with few guests. They were not able to sit shiva -- or mourn together at home -- as is Jewish tradition.

Funeral service workers in personal protective gear carried the casket, and a bulldozer shoveled dirt over the grave, Jeffrey Helmreich said.

Helmreich's widow and one of his sons attended, standing six feet apart.