I never learned of Ft. William and Mary in Portsmouth, NH until very recently. Perhaps kids in Boston are more focused upon the finer details of events leading up to the American Revolution, but anyway…
What other British forts were on American soil? Do any exist today, if only as ruins? What is left of Ft. William and Mary?
The remains of Fort Duquesne (French) and Fort Pitt (British) are in downtown Pittsburgh.
Fort Ticonderoga was originally constructed by the French, but captured by the British, and eventually the Americans during the Revolution. It has been mostly restored, and I enjoyed visiting it when I was younger.
Come to the Mackinac straits area and check out Fort Mackinac on Mackinac Island and Fort Michilimackinac (use the same URL as above) at the northern tip of the lower penisula (Mackinaw City). Both well worth the trip and Fort Michilimackinac offers a truly magnificent view of the Mackinac Bridge.
A really great example of French and Indian War forts is Fort Frederick in Maryland. The walls were stone instead of the typical wood (like Fort Duquesne and Pitt) and so still has the walls intact.
Fort Vancouver was established by the Hudson’s Bay Co (which like many British ventures was essentially the government over large areas). Fizzled out after the 1846 boundary treaty.
Which sparks a followup question: Was there a later active British fort in what is now US territory? There was a long term British “camp” in the San Juan Islands during and after The Pig War but I don’t know if there was an actual fort.
I don’t know about new forts – but the British didn’t immediately leave after losing the American colonies:
Another good example is the reconstructed Fort Necessity. That gives you a great idea of the true nature of most of these slapdash forts.
Plus, the surrounding meadow and woods is much like it was when Washington fought there - as a colonel loyal to the King.
Fort Nisqually is another I believe
Whatever became of Castle William in Boston harbor? Hate to think such valuable real estate is still undeveloped.
Fort William Henry in Lake George, NY, built during the French and Indian War. It’s a museum now, pretty much the way it was back then.
The British scuttled it in 1776 (or whatever the fort equivalent of scuttling is). We eventually built the pentagonal Fort Independence on the island and put in a causeway and a hamburger stand.
Here in Toledo area (actually in the city of Maumee), we have Fort Miami, which was built by the British in direct defiance of the terms of the Treaty of Paris of 1783. It was the supply fort for the Indian forces which were defeated at the Battle of Fallen Timbers by General “Mad” Anthony Wayne. Interestingly, the British refused admittance to the defeated Indian troops after the battle, which allowed Wayne to follow the Indians and inflict further losses upon them. Fort Miami was abandoned by the British following Jay’s Treaty, but they reinvested the fort during the War of 1812, when it stood across and down the river from the newly built Fort Meigs.
Fort Miami is only a site now, which is protected and on which you can see the outlines of some of the structures. Fort Meigs is a fully restored fort, with a very wonderful visitors’ center, recreations, etc. 
Fort Ligonier in western Pa., which dates to the French and Indian War, is worth a visit: http://www.fortligonier.org/
Rebuilt by 1808 and renamed “Ft. Constitution,” and now open to the public as a NH state park. See: http://www.nhparks.state.nh.us/ParksPages/FortConstitution/FortConstitution.html
PBS just had a half-hour special on Ft. Niagara, which started as a French “peace house” (fortified trading post) but over time was built up into a complete river fort. Captured by the British in the French and Indian War, then turned over to the Americans, recaptured by the British in the War of 1812, again turned back over to the Americans, and now a NY state park: https://oldfortniagara.org/
It depends entirely on whether they’re able to find a local restaurant that makes the curry dishes they know from home. Switching diets can result in digestive upset and…
Oh, forts. Never mind.
Here’s my picture of Fort Necessity. Two interesting facts about the fort:
(1) this was basically where the French and Indian War started, which became the Seven Year’s War between Britain and France – a war which has been described as the “first world war”;
(2) this is where George Washington suffered his only military defeat, since he and his forces surrendered to the French here.
But it’s not much of a fort: just a wooden wall with shallow trenches outside, built very quickly from the locally available materials.
In Florida: Fort Gadsden on the Apalachicola River.
In South Carolina: The star fort at Ninety Six.
In Georgia: Fort Wormsloe, Fort King George, Fort Frederica, Fort Morris.