The furnaces, support buildings and surrounding community have been preserved as a historical site and museum, providing a glimpse into Lebanon County's industrial past.

The site is the only intact charcoal-burning iron blast furnace in its original plantation in the Western Hemisphere.

Cornwall Iron Furnace was one of many ironworks that were built in Pennsylvania over a sixty-year period, from 1716 to 1776.

Namely, vast stands of timber for the production of charcoal, running water to operate the bellows, and an ample supply of limestone needed to add flux to the smelting furnaces.

Grubb's plans were further helped by the fact that the magnetite at Cornwall was either very close to or on the surface of his land.

These centers of iron production were usually located well away from the heavily cleared farmlands and were nestled in the Ridge and Valley section of Pennsylvania.

Cornwall Iron Furnace was an excellent fit for the agricultural-based economy of the Thirteen Colonies.

Curtis operated the Cornwall Furnace and lived on site; circa 1773 he built the original 19 rooms of the mansion that still stands prominently next to the property.

The ironworks were major suppliers to the Revolutionary War effort, and George Washington once visited to inspect the operation.

It was an economical way to test the market without having to invest in building the much more efficient and profitable blast furnace.

It consists of a pit or chimney with heat-resistant walls made of earth, clay, or stone.

These pipes, called tuyeres, allow air to enter the furnace, either by natural draft or by forced with a bellows.

Limestone could also be added to the bloomery, about 10% of the ore weight, which would act as flux and help carry away impurities.

The small particles of iron produced in this way fall to the bottom of the furnace and become welded together to form a spongy mass of the bloom.

Grubb's furnace was built in the form of a tall chimney-like structure lined with refractory brick.

The resulting "blast" promotes combustion of the charcoal (more modern furnaces use coke or even anthracite), creating a chemical reaction that reduces the iron oxide to the base metal which sinks to the bottom of the furnace.

The pig iron produced by the blast furnace is not useful for most purposes due to its high carbon content, around 4-5%, making it very brittle.

For other purposes further processing is needed to reduce the carbon content to enable iron to be used for tools or as a construction material.

In the late 18th century, this began to be displaced by 'potting and stamping', but the most successful new process of the Industrial Revolution period was puddling.

The fires were allowed to smolder for ten to fourteen days, under the careful, round the clock, supervision of the collier.

The iron works support staff included a company clerk, a host of teamsters, woodcutters, the colliers, farmers and household servants.

There were three groups of workers at Cornwall Iron Furnace: Free labor, indentured servants and slaves.

Slavery was legal in Pennsylvania until it was gradually abolished beginning in 1780 when the importation of slaves was prohibited.

Robert Coleman rose from a holding clerkship at a prothonotary's office in Philadelphia to bookkeeper at Cornwall Iron Furnace to becoming Pennsylvania's first millionaire.

George Dawson Coleman married Deborah Brown of Philadelphia and had several children including Ann Coleman who moved to France and revitalized Château de Villandry (alongside her husband Joachim Carvallo).

George acquired greater control of the ore mines at Cornwall and was able to experiment with iron furnaces that were fueled by anthracite coal instead of coke.

Cornwall Furnace no longer earned a profit in its last ten years of operation and the last owner, Robert Habersham Coleman, had it shut down on February 11, 1883.

In 1932, the furnace and ancillary buildings were deeded by Margaret Coleman Buckingham and have since been restored and open to the public.