I know Groton primarily because of the Sub Base there. In about 1957, my husband joined the Naval Reserve as a submariner. When he was at the Naval Academy he did his junior year cruise on a submarine, and I went to visit. I ate dinner with him on one of the submarines
Groton became known as the Submarine Capital of the World when the Electric Boat Division of General Dynamics delivered 74 diesel submarines to the Navy in World War II. This was followed in 1954 with the launch of the USS Nautilus, the world's first nuclear-powered submarine, now permanently berthed at Goss Cove near the Submarine Base.
Today Groton has more than just the submarine industry. When we went looking for the Avery Point Lighthouse (on the University of CT grounds) we passed a large pharmaceutical manufacturing facilty.