The island's last two monarchs lived in it from 1882 to 1893, but it later fell into disrepair—until it was renovated and reopened in 1978.
A fire destroyed it in 1969, leaving it to become the ruins you see today in the middle of the Hudson River in Beacon, New York.
It took 15 years to build this 13th-century replica of a Tuscan castle, located in the middle of California's Napa Valley. The wait was worth it: It's a huge tourist attraction today, offering tours and wine tastings.
The Sinagua people built this 20-room castle on a cliff approximately 800 years ago in what is known today as Camp Verde, Arizona.
Located in Tarrytown, New York, this 1838 mansion overlooking the Hudson River is one of the country's best examples of Gothic Revival architecture
Newspaper mogul William Randolph Hearst built this Julia Morgan-designed castle in San Simeon, California, to serve as his private residence.
In 1900, the owner of New York's Waldorf Astoria Hotel, George C. Boldt, built this 120-room castle for his wife, Louise, on an island in the St. Lawrence River in Alexandria
Henry Chapman Mercer, an archaeologist, artifact collector, and tilemaker, built this beauty in Doylestown, Pennsylvania, from 1908 to 1912.