[There are many people who know a lot more than I do, but here are some interesting bits that I've picked up so far.]
Around 1730, John Jacob Huber set up a tavern on a popular trade route through Lancaster County. (This tavern is now the Forgotten Seasons B&B.) Business must have been very good, because he then started Huber Furnace (later renamed Elizabeth Furnace) where the 501 and Pennsylvania Turnpike now meet.
James Old, owner of Quittapahilla Forge in Lebanon and part-owner of Hopewell Forge in Berks County, bought some property around Hammer Creek from Huber and built Speedwell Forge, as well as a small home for himself and his family.
Peter Grubb owned the Cornwall Iron Furnace as well as the Cornwall iron mines, the richest source of iron ever found in America. Peter Grubb hired Robert Coleman, an accountant from Ireland, who later left Cornwall and joined James Old, even living with his family at Speedwell Forge.
In the meantime, “Baron” Henry William Steigel married Elizabeth, Huber’s daughter, and took over Elizabeth Furnace five years later. He went on to buy Charming Forge in Womelsdorf, founded the town of Manheim, and then (what he was made famous for) opened a glassworks. Unfortunately we had overextended himself and was thrown into debtor’s prison and his assets were sold. Additional information about the Baron can be found here and here.
Judge George Ege (pronounced “eggy”), who owned aeveral other furnaces, bought Charming Forge from Stiegel’s creditors, and allowed Stiegel to live out the rest of his life there, teaching at the nearby school (which Stiegel had founded.)
Robert Coleman, meanwhile, married Anne Old, James’ daughter, and became an ironmaster himself when he leased Salford Forge. Later, he purchased it, as well as Elizabeth Furnace from Stiegel, Cornwall Furnace, and many others. He received Speedwell Forge from his father-in-law in 1784, but never lived in the mansion again. (Nevertheless, he expanded it, adding the eastern wing in the popular Georgian style.)