Fort Ontario

This fort was destroyed three times and rebuilt three times, and the version you can walk into is the fourth answer to the same question.

Fort Ontario stands on high ground on the east side of the Oswego River in the City of Oswego, New York, looking out over Lake Ontario. New York State Parks describes what visitors see today as the star-shaped fort dating to the early 1840s.

The first one went up in 1755, during the French and Indian War, one of several British forts guarding the east end of Lake Ontario and bolstering the defences already at Fort Oswego across the river. It was called the Fort of the Six Nations then. French forces destroyed it during the Battle of Fort Oswego in 1756 and the British rebuilt it in 1759. At the close of Pontiac's War, Pontiac urged moderation and travelled to New York, making a formal treaty with William Johnson at Fort Ontario on 25 July 1766.

In July 1778 a detachment from the 3rd New York Regiment destroyed the fort after the British abandoned it. The British came back and rebuilt in 1782, survived an aborted attack by Colonel Marinus Willet in 1783, and held the place until 1796, after Jay's Treaty. British forces destroyed it again in 1814 during the War of 1812. After a period of disuse it was rebuilt during the American Civil War.

The present fortifications are pentagonal with five bastions, a layout similar to Fort Jackson in Louisiana. It was designed for heavy cannon mounted en barbette, firing over the parapet in the open, with howitzers in casemates built into the bastion ramparts. The scarp walls are pierced with rifle loopholes of varying design, reflecting the preferences of the different engineers who oversaw the work.

In the 20th century it served as a military hospital, an infantry base, an induction centre and a Second World War refugee camp. The Safe Haven Holocaust Refugee Shelter Museum operates in a building just south of the fort. It was listed on the National Register in 1970, and some buildings are still used for Army Reserve training.