Nestled in Potapsco Valley State Park, a bit west of Baltimore is Lost Lake. I remember my Granddad taking me there many years ago. This tunnel under the B&O tracks was one of my favorite places to spend time while he fished. Sadly the B&O tracks no longer run over here, they now are the CSX tracks. But the park has been ‘improved’ over the years and the road now leads to picnic and camp grounds.