his other area operations and built a home near the site. Today, the diversion tunnel and some "slag" are about all that remain of his mill operation. The Montgomery Bell Tunnel is a Historic Civil Engineering Landmark. Also at the "Narrows of the Harpeth" is a prehistoric site known as Mound Bottom, noted for the complex earthwork constructions built from 950 and occupied into the 15th century. This area has several ceremonial and burial earthwork mounds of the Native American Mississippian culture, which preceded those historic tribes of the area known to European encounter. Bell's diversion tunnel and the sheer bluffs nearby are now part of the Narrows of the Harpeth section of Harpeth River State Park, a linear park connecting several natural, historic, and archaeological sites along the lower Harpeth. From this historic site, the flow becomes generally more northerly, but still greatly meandering. The Harpeth soon forms the line between Dickson and Cheatham counties for the last part of its course. A few miles above the mouth are what are known as the Three Islands; the U.S. Army Corps of Engineers proposed siting a dam near this location on several occasions and did some preliminary study. It was not supported by a favorable cost-benefit ratio and the project was never built. The lower portion of the Harpeth is very popular with canoeists, supporting canoe-outfitting and related businesses. The mouth of the Harpeth into the Cumberland is near Ashland City, the Cheatham County seat. Near the mouth is a bridge on State Route 49 named in Montgomery Bell's honor. The mouth is just below the Cumberland's Harpeth Island, and is somewhat submerged by the backwaters of the Corps' Cheatham Dam. After the removal of the lowhead dam in the city of Franklin, the Harpeth is Tennessee's second-longest unimpounded stream (the longest being the Buffalo). Name The origin of the name "Harpeth" is controversial. It is often claimed that the river was named for America's first known serial killers, the Harpe brothers, known as "Big Harpe" and "Little Harpe" who were in the area in 1797; this is erroneous since the name existed on maps and documents as early as 1784, predating their fame. A late-18th-century map, published in London, purportedly shows the steam as the "Fairpath"; there is some dissension about whether the name is of Native American origin or perhaps a corruption of the rather common English name