The Narrows of the Harpeth combines notable natural and cultural features, including a long narrow limestone wall encircled by a five mile loop of the river that returns to within 200 feet of itself, evidence of habitation beneath a rock shelter on the bluff dating back nearly eight thousand years, and the site of Pattison Forge with its view of Montgomery Bell's tunnel. Around 1818 to 1820, Montgomery Bell had African American slaves excavate a 200 foot tunnel, about eight feet high and fifteen feet wide, through the limestone bluff at the Narrows so water diverted through it could power water wheels and trip hammers that transformed hot brittle pig iron billets into malleable iron bars and plates. After Pattison Forge began operation, access by foot, wagon, or pack mule was only by way of the Narrows Gap, and its products were carried through the gap to markets in Nashville and Franklin or floated down the Harpeth and Cumberland rivers to Clarksville for shipment by steamboat. Bell owned and operated Pattison Forge, named for his mother's maiden name, from 1832 to 1854, after which James L. Bell ran it until it closed during the 1860's, and the forge never reopened after the Civil War as Tennessee's iron industry remained depressed. In the early 1880's, the Bell descendants sold the Narrows of the Harpeth, and the tunnel later powered a saw mill and then a gristmill before a flood washed the gristmill away in the mid 1890's. Montgomery Bell, born January 3rd, 1769 in Chester County, Pennsylvania, was one of nine children of John and Mary Pattison Bell, pursued several businesses, moved to Tennessee around 1800, learned the iron industry while working at Cumberland Furnace under James Robertson, then bought the furnace and went on to build forges across Tennessee's iron belt, earning recognition as Tennessee's First Capitalist. In 1850 in London, England, he won first prize for producing the best iron in the world, and after his death on April 1st, 1855, at age 86, he was buried across the river within sight of his tunnel.