Will Millard returns with more of Wales's hidden wonders as he explores some of the country's forgotten historic buildings.

In Wales, we are in danger of losing vital pieces of history that tell us who we once were. Beautiful buildings that are architectural gems but also some of the most endangered in the UK. These extraordinary structures, which can give us vital insights into how we once used to live, are in danger of disappearing forever.

From extravagant mansions to a 500-year-old farmhouse, crumbling chapels to a massive military fort, and from spectacular industrial sites to a stunning 19th-century theatre, Will travels the length and breadth of Wales to find some of our most vulnerable old buildings, telling their incredible histories and meeting the passionate individuals who are trying to rescue them before it is too late.