A section of Hutcliffe Wood Road, Millhouses, collapsed on Sunday afternoon, leaving a hole about 8ft deep.
Sheffield Council quickly closed the road and diverted traffic while engineers try to figure out what happened.
Locals have their own theories. Pensioner Phil Lovell, 87, said he was sure the hole was caused by the collapse of one of the old drift mines that were driven into the steep wooded hillside.
He said that, as a child, he played in one mine further up the slope but he thought another ran right under where the hole appeared.
“As soon as I saw it on TV I knew what it was,” Mr Lovell said.
“I’m 87 so I’ve lived round here a long time.
“I used to live down the road and there were two drift mines.
“We used to come on our bikes and we used to go down the one opposite here.”
Mr Lovell said the drifts were dug to mine ganister, a stone used to line furnaces in the steel industry. Old ganister mines litter many areas of Sheffield.
He said there was a local legend that the mines went right under the Woodseats area of the city.
But he dismissed other rumours that the tunnel at the bottom of the hole had a more romantic link to the nearby Beauchief Abbey.
Contractors later moved in to begin the task of filling the gaping hole with concrete.
A spokesman for the council’s Streets Ahead road repairs programme said: “A hole in the road appeared on Sunday, April 24, in Hutcliffe Wood Road. We are investigating the cause of the hole and have closed the road and the footpath to ensure the safety of the public.
“We have diversion routes in place and encourage the public to adhere to these so we can ensure their safety. We are working as quickly and as safely as possible and will re-open the road as soon as we can.”
Drivers are being diverted via Abbey Lane, Abbeydale Road South and Archer Road, while pedestrians can use Folds Lane, Abbey Lane, Abbeydale Road South and Archer Road.