Fort Constitution inside, has these two long berms with raised gun mounts along each wall. Note the center pivot mount and the outer ring for travel for the rear of the canon with pin holes for specific degree stops!
The Fort is on the island of New Castle, New Hampshire, at the mouth of the Piscataqua River estuary. Sally Ports are the protected doorways for troops inside the fort to rally at, and are used as protected entrances and exits into the fort. For Fort Constitution, these are located under the gun berms.
