Will Millard discovers the hidden history of Wales. He begins his tour in the north, uncovering long-unseen historical gems such as the biggest abandoned slate mine in the world.

In this three part series, writer and adventurer Will Millard discovers the hidden history of Wales by exploring forgotten, secret and usually inaccessible locations that show the country as you've never seen it before.

On an intriguing, exhilarating and sometimes dangerous journey, Hidden Wales with Will Millard offers unprecedented access to places you rarely get to see. Starting in the north and working his way south, Will reveals natural wonders hidden beneath the landscape, the abandoned buildings that tell us where Wales has come from and the modern marvels of engineering that show what the country might become.

In this first episode, Will begins his tour around Wales in the north of the country. From the biggest abandoned slate mine in the world to a forgotten mansion concealed in a wood, and from a decommissioned nuclear power station to a Victorian invention lying at the bottom of the sea, Will uncovers historical gems in parts of north of Wales you never knew existed. It could also be your last chance to see some of the Welsh history that is vanishing right in front of us.