By Bogdan Oporowski – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=21166547
Fort Proctor near Shell Beach, Louisiana is a ruined fort (also referred to as Beauregard's Castle) built in the mid-1800s. Surrounded by water, the brick castle is largely intact externally so is still an impressive sight however it is not accessible on foot.
Fort Proctor is inaccessible on foot. The nearest town is Shell Beach, LA.
Castle Gould, Sands Point Preserve Conservancy, New York is a 100,000 sq ft limestone castle built in 1904.
The Pink Castle in Flintridge, California is a prominent, castle-like residence built in 1911.
Hillcrest Museum Castle in Souris, Manitoba, Canada (previously Squire Hall) is one of Canada’s most important heritage properties.
Ridge Rook Castle in Rogersville, Tennessee is a castle-like private residence with crenellated roof-line set in the Clinch Mountains.