Jim Larkin

This week, Secret Sights visits the largest old factories in Ireland, including a huge forgotten plant in Portlaw, Co Waterford, which employed 2,000 people in the mid-19th century.

Surrounded by a model village, the workers were supplied with houses with hot water. This was virtually unheard of anywhere at the time, says presenter Rob Vance.

He also visits a secret bunker on the Shannon, designed to repulse Napolian. And Rob tells the story of how in 1807, two ships carrying Irish solidiers (who had signed up for British service overseas because they couldn't get jobs here) and their families set sail from Dublin Bay, looking forward to a new life. However, before their journey even began, a violent snowstorm broke out and both boats got crashed against the rocks - all on 400 on board, bar nine, perished.

Now in its third series, Secret Sights continues to unearth fascinating nuggets of information, exploring little known parts of Ireland and Irish history, this time focussing on the 'Long Century' that ended in 1922.