Not our usual fare because you can in no way look at this and say it is a castle but it is none the less very interesting from a historical viewpoint and can be described as robustly built. If you have an interest in Industrial history, specifically the innovation that allowed the production of cheaper, better quality steel. The “basic steel process” or the “Gilchrist-Thomas process”, named for the industrial chemist Sidney Gilchrist Thomas and his cousin Percy Gilchrist who was a chemist at the Blaenavon Ironworks came about when Sidney discovered a solution to the problem of phosphorus in iron, which resulted in the production of low-grade steel. By using dolomite or sometimes limestone as a lining for the Bessemer converter rather than the usual clay they were able to remove the phosphorus and produce a better quality of steel at a fraction of the price. It also produced a byproduct of phosphate fertilizer.