This is the only entrance to Fort Clinch along the St. Marys River east of Jacksonville, FL The fort was built in the early 1800’s to protect the harbors up river - which now include a major submarine base for the USNavy - but I don’t thing they depend on the fort’s armaments. The sally port was from the old meaning of sally as in bursting forth and would be used to attack the attackers of the fort or for going out on a mission (“sally forth”) from the fort. There are still sally ports today in prisons, for example. A fort’s sally port almost always had a cannon located so if the port was breached by attackers, the first thing they met was a burst of grapeshot from the cannon. This fort usually has a cannon by the flag pole but it was out back getting a repair.

Clearly the educational value of Two Lane Touring is staggering. If you pass the test I offer, after 4 years of viewing, I imagine many prestigious universities would be happy to grant you scores of credits.