The ironworks at Österbybruk were established by King Gustav I of Sweden with the help of German experts during the 16th century and specialised in making munitions.
During the 17th century the factories were merged with Lövsta and Gimo, under the directions of Louis De Geer, making it the second largest ironworks in Sweden.
Since De Geer recruited skilled iron workers from the Walloon Region of Belgium, these ironworks became known as the Walloon factories ("Wallonbruken").
The iron ore processed in Österby came from the Dannemora mine and was noted for its purity.
Iron bars produced at these ironworks were stamped with a "Double Bullet" mark, which guaranteed high and consistent quality.
Such iron became reputable in England, where it was used by the steel industry in Sheffield.
In 1758, the ironworks was sold to the Grill Trading house, at that time owned by Claes (I) and Johan Abraham.
The trading house was discontinued with the death of Johan Abraham in 1799, and the ironworks was sold to Anna Johanna (III), the wife of Adolf Ulric.
The factory passed through several owners until it was closed in 1983.

In 1763, Claes (I) started construction of the mansion at Österbybruk.
The mansion incorporated the two wings already built in the 1730s; the west wing which served as housing for one of the ironworks caretakers and the east wing containing a chapel.
The mansion was not completed until 1780, due to the decline of the East India trade, accusations of financial misconduct against Claes and Johan Abraham and the banking crises in Amsterdam in 1763.
As of 2014, the manor is owned by the Bruno Liljefors Foundation.
His studio in one of the buildings is preserved and is on occasion open to the public.
The ironworks at Österbybruk were established by King Gustav I of Sweden with the help of German experts during the 16th century and specialised in making munitions. During the 17th century the factories were merged with Lövsta and Gimo, under the directions of Louis De Geer, making it the second largest ironworks in Sweden. Since De Geer recruited skilled iron workers from the Walloon Region of Belgium, these ironworks became known as the Walloon factories ("Wallonbruken"). The iron ore processed in Österby came from the Dannemora mine and was noted for its purity. Iron bars produced at these ironworks were stamped with a "Double Bullet" mark, which guaranteed high and consistent quality. Such iron became reputable in England, where it was used by the steel industry in Sheffield. In 1758, the ironworks was sold to the Grill Trading house, at that time owned by Claes (I) and Johan Abraham. The trading house was discontinued with the death of Johan Abraham in 1799, and the ironworks was sold to Anna Johanna (III), the wife of Adolf Ulric. The factory passed through several owners until it was closed in 1983.
In 1763, Claes (I) started construction of the mansion at Österbybruk. The mansion incorporated the two wings already built in the 1730s; the west wing which served as housing for one of the ironworks caretakers and the east wing containing a chapel. The mansion was not completed until 1780, due to the decline of the East India trade, accusations of financial misconduct against Claes and Johan Abraham and the banking crises in Amsterdam in 1763. As of 2014, the manor is owned by the Bruno Liljefors Foundation. His studio in one of the buildings is preserved and is on occasion open to the public.
Grill family