DyF - upper works

These sections of the building include the charge house - very careful control of the proportions of charcoal and iron ore were required - something the early iron-masters regarded as their trade secret - otherwise the bloom produced could be too carbon rich and thus impossible to work effectively, or alternatively, insufficient charcoal would mean that the iron ore would be incompletely reduced to the sought after metal.
As this site had forced draughting, it should be classed as a "Catalan Forge" rather than a Bloomery.

en.wikipedia.org/wiki/Bloomery

The part of the building on the right is now a protected summer bat roost and breeding site for the lesser horseshoe species [ Rhinolophus hipposideros ] en.wikipedia.org/wiki/Lesser_horseshoe_bat