Bancroft's Castle, Groton Fire Tower, MA

• 4-star hike • 1½ mile out-and-back • Easy | Gain 180 feet • Groton, MA | Northeast Region . Views of Bancroft's Castle tower through the trees. Rising above the trees on Gibbet Hill in Groton, Massachusetts, a stone tower looks like the remains of a medieval fortress. It isn't. In 1906, Groton native General William Bancroft, a former mayor of Cambridge, began building a retirement estate on the hill. He named it Shawfieldmont and planned a grand mansion alongside a modest bungalow, but ran out of money before the larger house could be built. The project was abandoned, but the bungalow remained and took on a second life. It was repurposed as a sanitarium in 1918 and later served as a social hall for the Groton Hunt Club through the 1930s. A Fourth of July firecracker accident in 1932 burned down much of the structure, leaving behind the stone framework that locals now call "Bancroft's Castle." The trail begins at the large parking lot for the Gibbet Hill Grill, just outside Groton…