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 second episode, Will continues his tour around Wales by moving to both mid-Wales and the west of the country. From a lead mine that's thousands of years old and a beautiful cave with a very scary entrance to an abandoned sea fort and a derelict mental asylum,

In this final episode, Will completes his tour around Wales in the south of the country. From the resting place of early man to a lost mediaeval city, and from a forgotten prisoner of war camp to an abandoned coke works,

Will explores some Wales’s most intriguing and hard-to-access caves.

Will discovers the forgotten story of how Wales once led the world in copper production by visiting some extraordinary and abandoned locations.

Wales once led the world in the production of coal, exporting the black gold to the four corners of the Earth. Since that industry collapsed, much of the infrastructure has been destroyed, forgotten or hidden away.

Will travels to North Wales to discover the forgotten history of the slate industry. Welsh slate once roofed the buildings of the British Empire and the industrial revolution.

Will explores the hidden pieces of history from World War Two. Wales made a huge contribution to the war effort and the remote countryside was witness to many military activities.

In this final episode Will gains exclusive access to explore the usually inaccessible locations that are home to some of the biggest engineering projects in Wales, both past and present.