Begun in 1819, Ft. Snelling at the time was the remotest military outpost on the American frontier. (Now it's just a mile from the Minneapolis-St. Paul airport.) It was built to protect U.S. interests (read: fur trade) in this corner of the Louisiana Purchase and to keep peace among the region's Native American peoples even as the federal government laid claim to their lands. The fort did its job, but not without controversy: The slave Dred Scott based his bid for freedom on time spent here, and after the bloody 1862 U.S.-Dakota War, 1,600 Native Americans were imprisoned on the river flats below.
Why it's a treasure: Except for a brief interlude before the Civil War, Ft. Snelling was an active military post until after World War II, and the handsome house was where its commanders lived. It was built in 1820 of the same cream-colored limestone as the fort itself. Because the site slopes, the house has one story facing the parade grounds but three at the back, overlooking the confluence of two great rivers — the Mississippi, here flowing in a deep gorge, and the broad, island-dotted Minnesota. The lower level holds the original open-hearth kitchen and the office of Col. Josiah Snelling, for whom the fort was named. Furnishings are period antiques like those the Snellings would have brought with them from back East.
Why you'd want to live here: Because it's the best house in the fort, and the fort is stunning. The high-walled, diamond-shaped stronghold crowns a steep limestone promontory 10 stories above the junction of the rivers. Early visitors called it a "citadel in the wilderness" and likened it — with reason — to Gibraltar and castles on the Rhine.
Why you wouldn't: Come winter, you'd be bored and cold. Once the rivers froze, no steamboats could get through with fresh news or fresh faces. You'd have to sleep under heavy quilts because the only heat came from your room's small wood-burning fireplace, and the wood supply sometimes ran low.
The surprise: The modern cities of St. Paul and Minneapolis have encroached upon the fort, but from its ramparts, scenic views of water, woods and sky still stretch for miles.