The Doors of Durin,
Lord of Moria.
Speak, friend, and enter.
Did I find a possible entrance to the Mines of Moria?
This side quest comes courtesy of Topo Ranger. In it he had me exploring this culvert beneath the Columbia and Port Deposit Railroad sandwiched between the orange-blazed Conestoga Trail and the Norman Wood Bridge.
Unfortunately, it took more parkour skills than I possessed to keep my feet dry while traversing through the tunnel. All the more fun!
Finding the Culvert
You can access the culvert via the Conestoga Trail, where it intersects Route 372 near the Norman Wood Bridge.
Follow the trail down from the road. Follow the stream downhill to the culvert.