A 140-year-old Victorian colliery winding engine has gone on display to the public... for one day only!
The giant machine wound miners and coal at the Hetty Pit near Pontypridd.
Volunteers have spent a more than a decade restoring it.
Mike Griffiths went to see it in action.
Drive into Rhondda Valleys from Pontypridd and the Hetty Pit will be something of a landmark.
Formerly part of the Great Western Colliery, it hasn't been a working coal mine for more than thirty years.
Now a team of volunteers are determined to save the buildings that remain.
The main attraction - the steam winding engine that for more than a century helped transport miners underground.
The mine opened in 1875. For the last decades of its life it was part of the nearby Ty Mawr and Lewis Merthyr Collieries.
In 1983, it closed for good.
Lewis Merthyr is now a popular mining museum, but the Hetty has been largely off-limits.
Now, the public have had a rare opportunity to see inside.
Many of the volunteers have given up weekends over the last twelve years to restore the engine.
Some of them have a very special link with the site.
Running the engine isn't cheap, and these open days are a rarity.
The team now hopes to refurbish the giant headframe above the old mineshaft.