Brandywine Mansion (1750) - Coatesville, PA - Pre-Victorian Historic Homes on Waymarking.com

Brandywine Manor, dating from the latter eighteenth century, is located on South First Avenue, and is nearly flush with the current thoroughfare. Its core construction consists of two sections: a 21/4-story, stucco-over-stone (east) section, two bays wide, built circa 1750-70, is attributed to William or Peter Fleming; and a 2^-story (plus basement), stuccoover-stone (west) addition, three bays wide and slightly deeper, built 1788 by Moses Coates. Fronting these two early sections on the south is a two-level, shed-roofed porch (now enclosed). These elements comprise the house in which Rebecca Lukens lived. SOURCE

This is perhaps the most important contributing structure to the Lukens Historic District. Lukens is the oldest steel mill in commission within the United States. The Brandywine Mansion, located at 102 South 1st Avenue is significant and contributes as the founders of the Lukens steel dynasty lived here. The small house is the oldest structure in the Lukens Historic District. The original section, dating to the mid-1700s was built by the Flemings, early landowners in what is now Coatesville.

The property was purchased by Moses Coates in 1787. Coates, for whom the City is named, built the larger section of the house to the west. Farmer, inventor and the area’s first postmaster, Coates is believed to have entertained President George Washington here as he passed through this area in October, 1794 in route to Philadelphia after quelling the Whiskey Rebellion in western Pennsylvania. SOURCE

The outside of the house is a wreck; it is very messy and looks completed wasted. A huge section was recently removed in an effort to restore it to its original appearance before it was enlarged over the years. So, looking at it, one can easily see where an adjacent section was removed, as the ghost features from the removed structure are printed on the original structure. The new owners of the Steel company bought and then donated the mansion to the historical society, who has been in the process of restoring the house. The larger commercial section was added in the early 1920's for the Lukens Employees Store, which remained in operation until 1992. The property is now owned by Bethlehem Steel Corporation.

I found a few dozen websites as well as the original nomination form (NPS focus site). There is also a ridiculously detailed and complex site as long as a small book which details every possible aspect of the house which can be found HERE

There is an official PHMP historical marker here which reads: Historic Fleming house, purchased by Moses Coates in 1787. Acquired in 1810 by Jesse Kersey and Isaac Pennock, founders of the Brandywine Iron Works. Occupied 1816-1825 by Pennock's son-in-law, Dr. Charles Lukens, whose widow Rebecca continued and expanded the firm's operations following his death. Rebecca Lukens, who lived here until her death in 1854, gained renown for her vision and business capability. /

Additionally, the contributing properties here have individual interpretives. The one associated with the mansion reads:

The small house known as Brandywine Mansion is the oldest structure in the Lukens National Historic District. The original east section, closer to the road, dates back to the mid 1700s and the larger west section was added around 1788, shortly after the property was sold the Moses Coates. It is believed that President George Washington stopped at Brandywine Mansion in 1794 en route to Philadelphia after quelling the Whiskey Rebellion in western Pennsylvania. Moses Coates sold the house and 110.5 acres to Jesse Kersey and ironmaster Isaac Pennock in 1810. Mr. Pennock converted the farms sawmill into a rolling mill and his business, Brandywine Iron Works & Nail Factory, was the beginning of Lukens Steel Company. Mr. Pennock’s daughter, Rebecca, and her husband, Dr. Charles Lukens, moved to Brandywine Mansion in 1816. Together they began restructuring the mill to role plate iron by 1818. After Charles Lukens’ death in 1825, Rebecca assumed management of the mill; thus she is credited as being America's first and most prominent female industrialist. She continued to live in Brandywine Mansion until her death in 1854.