The classic series of United States ("US") commemorative coins includes several issues that depict a fort within their designs. Here's a brief look at them:
1925 Fort Vancouver Centennial Half DollarThe 1925 Fort Vancouver Centennial Half Dollar was issued to commemorate "the one hundredth anniversary of the founding of Fort Vancouver, State of Washington." The fort is located on the north side of the Columbia River in what is now Vancouver, Washington (just north of Portland, Oregon).
The fort served as a trading post for the Hudson's Bay Company ("HBC") which administered Britain's interests in the area; the area was jointly occupied by British and American frontiersmen, trappers and settlers. The fort was established by the HBC in 1825.
Fort Vancouver is presented in the background of the reverse of the half dollar, behind a fur trapper holding a rifle.
The original fort, unfortunately, was destroyed by a fire in 1866. The fort has been reconstructed using available photographs and/or drawings as references.

For more about Fort Vancouver and a couple of images of the reconstructed structure, see:
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Coins Depicting Places - Fort Vancouver1934 Daniel Boone Birth BicentennialFort Boonesborough is depicted (partially) in the background on the reverse of thr 1934-38 Daniel Boone Birth Bicentennial Half Dollar.

For more about the fort and an illustration of it, see:
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Coins Depicting Places - Fort Boonesbprough1934-38 Texas Independence CentennialThe reverse design of the 1934-38 Texas Independence Centennial half dollars include a depiction of the Alamo. The Alamo was originally a Spanish religious mission (built in 1718). It was repurposed as a fort by the Spanish circa 1803, and later used by the Texians during the Texas Revolution.

For more about the coin and the Alamo, see:
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Coins Depicting Places - The Alamo1936 York County, Maine TercentenaryThe obverse of the 1936 York County, Maine Tercentenary Half Dollar depicts Brown's Garrison, one of the first stockades built in York County, Maine (dating to the 1720s); it was located on the Saco River in present-day Saco, Maine.

For more about the coin and the Alamo, see:
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Coins Depicting Places - Brown's GarrisonFor more of my stories about commemorative coins and medals, including other coins depictine Places, see:
Commems Collection.