Big Pit, Wales' working mine museum, is lending its mine shafts to a firm creating a Welsh cheddar cheese.
Conditions in Big Pit are said to be ideal for maturing the cheddar
A Blaenavon company which makes four types of cheddar says the temperature 90m (300ft) underground is ideal for its 40kg (90lb) blocks of cheese.
The cheddar is kept in purpose-made boxes for two weeks while it takes on a distinctive "marbling" on its surface.
Cheddar cheese was traditionally matured in Somerset's Cheddar caves, from where it takes its name.
Big Pit cheddar was the idea of Susan Fiander-Woodhouse, who runs the Blaenavon Cheddar Company with husband Gerry Woodhouse.
She said: "Years ago, cheese was matured at Cheddar, and I thought it would be a perfect replica of the conditions that were used years ago, rather than having cheddar matured in big warehouses at it is today.
"The conditions are absolutely perfectly right for the cheese to take on its unique flavour. The temperature below ground is a constant 10.9 degrees."
The Big Pit cheddar takes on a 'marbling' which adds to its flavour
The scheme needed permission from both the local environmental health department and the National Museum of Wales, which runs Big Pit.
Paul Green, deputy manager of Big Pit, said: "Being as we see the mining museum as part of the community, we like to help local businesses, so anything we can do to help, we will."
Big Pit is set in the former coal and iron town of Blaenavon, which was made a World Heritage Site in 2000 in recognition of the role it played in the industrial revolution
In 2005, it won the Gulbenkian Prize, which aims to promote public appreciation of museums and galleries by highlighting the best work in the sector.