The complex, located in the Okamika district of Gizaburuaga, is a complex proto-industrial establishment and is probably one of the most interesting in the whole of Biscay.
It is a complex hydraulic installation. A large double forge made up of a huge coal bunker, several spaces for the collection of the vein and the billet, seles, three flour mills, a reservoir and a bridge with two eyes. A single column supports the entire roof. It is one of the most complex forges in the Basque Country. It was once one of the most important pre-industrial factories.
The owner of the surroundings, Pedro Bernardo Villarreal de Berriz, renovated most of its facilities at the beginning of the 18th century. The Bengolea dam is unique, unlike the other reservoirs in the area, with a single central abutment and a straight front.