Inner Pierhead Fort

It is positioned on the end of the inner breakwater, which abuts from the former dockyard of HMNB Portland.

The inner breakwater, including the fort, became Grade II Listed in 1978.

Prior to its construction, tests on the strength of Portland stone compared with granite was conducted by the Army.

Two butt walls were built, one in each stone type, and these were fired upon by HMS Blenheim.

[4] A 40 mm Bofors gun was added during World War II.