Built in 1467, Knappogue was vacant for more than 40 years when Mark Edwin Andrews, an oil executive and former assistant secretary of the Navy, bought the castle in 1966. The suite for overnight guests was restored as Andrews' private residence; with five bedrooms, four baths and a baby grand piano, the apartment sleeps ten. Both Charles de Gaulle and Ronald Reagan have stayed here.

Henry the Eighth was a frequent visitor at Leeds Castle, which dates from 1119. Overnight guests can stay in the Battel Hall Oast, a two-bedroom brick building where castle brewers dried their hops, or the Weir Cottage, a small one-bedroom duplex. The 300-year-old Gamekeeper's House sleeps ten and provides guests with a thoroughly modern professional-grade Aga stove to cook up the fish you'll catch in the nearby stream.

This nouveau castle opened in 2004, ten miles north of Beijing. Though it's the antithesis of an authentic medieval castle, it's worth a trip just for the wild confluence of Renaissance, Greco-Roman and Baroque architectural and decorative styles throughout the three main buildings that make up the complex. The wine culture center and the mural dome painting of Zeus, Bacchus and Apollo engaged in various activities complete the spectacle.

A former monastery that dates back to the 13th century, Backaskog was the summer residence of King Charles XV. Nineteen guest rooms and suites are available for guests to participate in a variety of activities, including opera nights, nature walks, even a ghost tour, since the castle is reportedly haunted. The castle is on the National Trust and the surrounding land is managed by the Swedish Forest Service.

This 115,000-square-foot, 115-room estate has variously served as a retirement home for sanitation workers, a radio operator school and a military school. Completed in 1919, the Oheka has 32 guest rooms and has been called the best place to get married on Long Island. Part of the movie "What Happens in Vegas" was filmed on location here.

Despite their centuries-long heritage, not many castles stay in the same family for more than a thousand years, but Chateau de Canisy has. Count Denis de Kergorlay is the latest to helm the estate, which has 24 rooms available for overnight guests, some furnished with beds and furniture that date to the 18th century.

General Eisenhower slept here on the top floor of Culzean Castle, the cornerstone of a 600-acre estate that dates back to the late 16th century. In fact, the Kennedy family—who have owned the property since 1569—specifically designed the apartment for the general, which today is maintained by the National Trust for Scotland. The six-bedroom suite is designed with flexibility in mind: While an extended family can easily fill the six bedroom suite, individual couples can also stay overnight in the suite.

The Chateau de Brissac is reportedly the tallest castle in France, with seven floors and 204 rooms. Brissac is in the Anjou section of the Loire Valley, and has served as the seat of the Dukes of Brissac since 1502, where the 13th Duke and his family live today. The four guest suites are decorated with an eye towards historical accuracy and a night here may make you dream of King Louis XIII, who visited the castle in 1602.

Olivia Hsu Decker was real estate agent to the stars, including Andre Agassi and Sharon Stone, before she purchased this circa 1695 castle and its 185 acres of gardens in 1999. She then painstakingly remodeled the chateau's 18 bedrooms to correspond to its 17th and 18th century roots. A special Da Vinci Code vacation includes a weeklong stay here along with tours of highlights from the movie, including visits to the Louvre, the Hotel Ritz and Saint-Sulpice.

Golfers will be pleased to know that the famous Old Course at St. Andrews is a mere 20-minute drive from Myres Castle, a 44-acre estate offering nine bedrooms for guests. The Queen's Room is named after Mary Queen of Scots, who slept in the room and planted the seeds of the sprawling Spanish chestnut tree that stands outside the window today.