Cincinnati's abandoned subway tunnel, which stretches 2 miles through Over-the-Rhine and northward, could be reimagined for another use after the city issued an informational request in late ...

One corner of the abandoned MBTA tunnel under Harvard Square, which is being explored as a potential new live events venue. David L. Ryan/Globe Staff ...

A railroad built a train tunnel near Fredericksburg 100 years ago, then later abandoned it. Then some of nature’s strangest creatures moved in.