Celebrating 50 years as a national historical park, the Chesapeake & Ohio (C&O) Canal’s 184.5 miles travel through four Maryland counties and the town of Georgetown, Washington, DC, and parts of West Virginia. Encompassing 20,000 acres of historical, natural and recreational treasures, it is the largest national park in Maryland. There are seven refurbished lockhouses along the canal, available for overnight stays. Three feature full amenities, and four are more rustic.

The Paw Paw Tunnel, located at milepost 155.2 of the canal, was an engineering marvel when it was built between 1836 and 1850. The tunnel saved six miles of canal construction but took much longer than the original estimate of two years. The 24-foot-tall and 3,118-foot-long tunnel is constructed of more than six million bricks. A narrow towpath runs parallel to the canal through the tunnel. If you go, take a flashlight and a sweater. It gets cold and dark by the time you reach the middle.

The C&O Canal National Historical Park ends in Cumberland, Maryland, where it connects to the Great Allegheny Passage, completing a continuous 330-mile bike route between Washington, DC, and Pittsburgh, Pennsylvania.