Important Reminder:The City Guide app will be sunsetting on December 15, 2024, with the web version to follow in early 2025. Please visit our FAQ to learn more or to download our Swarm app.
Chesapeake & Ohio Canal National Historic Park (at MM 155.20), Oldtown, MD
Hiking Trail · 9 tips and reviews
Brian Powell: Built in 1850, this 3,118-foot long tunnel carried the C&O Canal under a series of ridges and allowed it to bypass six miles of bends along the nearby Potomac River.