Furnace Mountain is the tallest peak of Catoctin Mountain

Catoctin Mountain

Catoctin Mountain, along with the geologically associated Bull Run Mountains, comprises the easternmost mountain ridge of the Blue Ridge Mountains, which are in turn a part of the Appalachian Mountains range...

 in Loudoun County, Virginia

Loudoun County, Virginia

Loudoun County is a county located in the Commonwealth of Virginia, and is part of the Washington Metropolitan Area. As of the 2010 U.S. Census, the county is estimated to be home to 312,311 people, an 84 percent increase over the 2000 figure of 169,599. That increase makes the county the fourth...

. It rises steeply from the southern banks of the Potomac River

Potomac River

The Potomac River flows into the Chesapeake Bay, located along the mid-Atlantic coast of the United States. The river is approximately long, with a drainage area of about 14,700 square miles...

 across from Point of Rocks, Maryland

Point of Rocks, Maryland

Point of Rocks is a community in Frederick County, Maryland. It is named for the striking rock formation on the adjacent Catoctin Mountain, which were formed by the Potomac River cutting through the ridge in a water gap, a typical formation in the Ridge-and-Valley Appalachians...

 and continues southward for 1 miles (1.6 km), reaching an elevation of 891 feet (271.6 m) before falling to a gap between it and an unnamed peak of 800 feet (243.8 m). Its name arises from the iron furnaces located at its base, which operated from the 1790s to the 1870s. The furnaces were used to process iron ore mined from the mountain, much of which was used to build the burgeoning city of Washington D.C..