Stopping by: Just north of Homestead in South Miami, the Coral Castle Museum is open every day, with audio stands that broadcast in several languages and guided tours also available.
Coral Castle, 28655 South Dixie Highway, Miami; +1 305 248 6345; admission $15
Auto Heir's Opus: Edsel & Eleanor Ford House (Grosse Pointe Shores, Mich.)
Story: Edsel Ford, lone son of auto titan Henry, would become president of Ford Motor Company by age 25, posing him the challenge of living up to his father's hulking legacy while setting his own bar over the next quarter century.
In addition to legendary cars like the Lincoln Continental, Edsel would build an English Cotsworld-style family estate that -- for sheer style, taste and grandeur -- tops dad's Fair Lane digs in nearby Dearborn.
Specs: A bold blend of classic European and modern (1930s) styles, the 60-room, 20,000-square-foot house designed by famed architect Albert Kahn is set on 87 lakefront acres in the heart of southeast Michigan's Gold Coast.
An extensive collection of art, period furniture and antiquities includes two Cezanne oil paintings, an original Diego Rivera and stained-glass window medallions dating to the 14th century.
Stopping by: Standard 50-minute guided tours explore the home's major rooms, including the English-baronial-style gallery and a contrasting art deco room done by eminent industrial designer Walter Dorwin Teague.
Behind-the-scenes and special interest tours delve deeper into the property and its stunning grounds.
Edsel & Eleanor Ford House, 1100 Lake Shore Road, Grosse Pointe Shores, Mich.; +1 313 884 4222; admission to all areas $15
California Headliner: Hearst Castle (San Simeon, Calif.)
Story: Hearst Castle's predecessor was Camp Hill, a tract of ranchland on the central California coast acquired by 19th-century mining magnate George Hearst for family campouts.
After inheriting the property in 1919, George's son -- newspaper mogul William Randolph Hearst -- reportedly told noted architect Julia Morgan, "We're tired of camping out in the open ... I would like to build a little something."
Specs: More than 28 years and 80,000 square feet later, the estate boasted the 115-room Casa Grande and three Mediterranean Revival-style guesthouses, with 27 acres of gardens.
Borrowing from just about every classic European style, castle highlights include the spectacular Neptune pool, an indescribably ornate main library (one of two on the property), Mr. Hearst's private Gothic suite and one of the world's most extensive (and manically collected) stashes of art and artifacts.
Stopping by: Now a California State Park, the property offers four separate tours covering various floors of Casa Grande and the areas of the estate.
A special Evening Tour (spring and fall only) lets visitors experience the mansion at twilight while docents play out the roles of 1930s houseguests and staff.
Hearst Castle, 750 Hearst Castle Road, San Simeon, Calif.; +1 800 444 4445; admissions start at $25
Greatest Showpiece on Earth: Ca' d'Zan (Sarasota, Fla.)
Story: Inspired by their favorite Tuscan villas and Venetian palaces, circus tycoon John Ringling and his wife, Mable, built a 1920s Mediterranean Revival-style dream home that would become known as "the last of the Gilded Age mansions" -- and the best place for a Gatsby-style party in southwest Florida.
Falling into state hands (and some neglect) after Ringling's death in 1936, the huge waterfront mansion overlooking Sarasota Bay entered its second heyday with a recent $15 million restoration effort.
Specs: The 36,000-square-foot, five-story (plus full basement) property totals 56 rooms, including 15 bathrooms.
It's adorned with Gothic arches, Mexican onyx columns, priceless 17th-century tapestries and a custom-made 1892 Steinway piano in the two-story great court, dolloped with an 81-foot Belvedere tower.
Stopping by: Docent-led tours of the mansion's main living space and a special Private Places tour through less frequented areas run daily.
After the house tour, you can see the estate's famous art museum, which houses one of the nation's finest collections of 17-century Baroque works.