The Nantyglo Roundhouse complex is a unique relic of the Industrial Revolution. It was built in about 1816 by Joseph and Crawshay Bailey, the Ironmasters of the Nantyglo Ironworks, as a defended refuge against armed revolt by their workforce. In effect, it was the last private castle built in Britain. No other site in Wales gives so stark a reminder of the bitter conflict between Ironmasters and workforce. The towers symbolise the social upheaval which gave birth to the Chartist Insurrection and which would eventually create the modern labour movement. Properly conserved and consolidated, the Roundhouse Complex has huge potential as a heritage centre telling the turbulent story of a key period in Welsh history. It would serve as an invaluable educational resource for local people and an attraction for visitors from further afield.
The Nantyglo Roundhouses and the associated agricultural range are Grade II* listed buildings.