Built at the falls-line of the (Dividing line of the Coastal Plain, the Piedmont Plateau) Big Gunpowder River in eastern Baltimore County, Maryland, the plant was started as a slitting and nail-making company.
Where the main channel of the Gunpowder once was and where sea going ships rode at anchor is now a corn field on the Mount Peru estate.
One rolling mill an immense stone structure abandoned more than twenty years ago still stands and is almost covered by the rank luxuriance of the Virginia creeper.
The works were owned and operated by that Patterson family of which Madame Elizabeth Patterson Bonaparte was a member, who sold the whole tract of one hundred and thirty four acres known as Bald Hill to the city of Baltimore for water privileges for twenty thousand dollars.
The city resold it and it is now the property of Levi Furstenburg.The Joppa Iron Works closed around 1865 with the death of Edward Patterson.