Tributes have been paid to the man who set up Clearwell Caves in the Forest of Dean as a tourist attraction.
Ray Wright, who reopened the mine as a working museum, has died aged 85 after a long battle with bone cancer, his family said.
The caverns near Coleford attract about 50,000 visitors each year.
They were mined for iron ore and red ochre for more than 4,000 years until the mine closed in 1945. They were reopened by Mr Wright in 1968.
Jonathan Wright said people "thought he was crazy" when his father first suggested opening up the underground caves.
"He wanted to show people the work the miners had done. People just thought he was mad.
"He stuck at it and worked away at it and gradually opened up the caverns, and people came.
"Gradually, people began to realise these were fascinating workings, that Ray was making something quite unusual and interesting.
"The caves are a tribute to his vision."
David Broadbent, of the Wye Valley and Forest of Dean Tourism Association, said Mr Wright had been "a font of knowledge about the forest's history".
Mr Wright was secretary of the Forest of Dean Freeminers Association for more than 30 years, and was one of four current Verderers of the Forest of Dean.