According to the American Association of Realtors, May is the time of year when Americans turn their attention to real estate. We buy and sell the greatest number of houses, perform annual cleaning rituals, plant gardens, and undertake the biggest home renovation projects, once clement spring weather is here to stay. For the National Trust for Historic Preservation (tel. 202/588-6000;, May is also Preservation Month, when local communities celebrate their oldest and or most distinguished homes with tours and other events.

What better time of year to take a road trip and visit some of these architecturally significant properties? With information from the National Trust and the American Institute of Architects, we culled a list of ten architecturally significant buildings across the United States. Of course, you needn't bother to wait until spring to visit them. Whether you're peering in for voyeuristic thrill, mining ideas for your own home, or buffing up on history, historic house tours are a fun way to pass the remaining months of winter chill.

Many of these tours require advance reservations. Please check individual websites for opening hours, prices, details and, in many cases, virtual tours. For properties near you, you can search the National Trust's site by state as well (from the home page, click "The Trust in Your State").

Biltmore Estate (tel. 800/624-1575;; Asheville, NC)

Though architect Richard Morris Hunt completed the Biltmore estate in 1895, as a retreat for George and Edith Vanderbilt in the mountains of western North Carolina, the four-acre mansion -- that would be the size of the building itself -- remains the largest private residence in the United States. Treasures include the 250-room mansion, Napoleon's chess set, paintings by Renoir, and the home's original furnishings and technologies -- which were advanced for its day and included electric lights, central heating, and refrigeration. A variety of tours on the estate, which was built to be self-sustaining, encompass the house, winery, farm village and gardens.

Eames House (tel. 310/459-9663;; Malibu, CA)

Charles and Ray Eames built their house in 1949 as part of the Case Study House Program, conducted from the mid 1940s through the early 1960s by Arts and Architecture magazine. The case study houses were built and furnished by design-architects using postwar materials and techniques, and the Eames conceived their place -- Case Study House 8 -- as a home for a married couple who were essentially apartment dwellers. For mid-twentieth-century design aficionados, the house has become a mecca -- known as a laboratory for the prolific couple's experiments in architecture, furniture design, industrial design and manufacturing, filmmaking, and photographic art -- though it's open only for drive-by tours of the exterior.

Fallingwater (tel. 724/329-8501;; Bear Run, PA)

In the laurel highlands of western Pennsylvania, the former residence of retailers Edgar and Liliane Kaufmann is widely regarded as Frank Lloyd Wright's masterwork, completed in 1938. The reinforced concrete and stone property recently emerged from extensive restorations, which rescued its famous cantilever from collapsing into the stream that rushes past the house over bedrock. The Western Pennsylvania Conservancy maintains the home and recommends reserving an entire day to visit the sublime landmark structure and surrounding river valleys, forests, and waterfalls, from which the house seems to be a natural outgrowth.

Farnsworth House (tel. 630/552-0052;; Plano, IL)

Ludwig Mies Van der Rohe's transparent house in a green landscape overlooking the Fox River was his first major residence in the U.S. Built in 1951, it's considered a masterpiece of the International Style, the name adopted for the Bauhaus school after its proponents emigrated to the U.S. to escape Nazism. The house is essentially a single-room glass box that seems to float, on a pedestal five feet above the ground. With its perfect proportions and utter simplicity, the house has often been called a glass temple, and it served as the inspiration for his friend Philip Johnson's own glass house in New Canaan, Connecticut (see below). Owned by the National Trust since 2003, the property reopens to the public from April 1 through November 30.

Fonthill (tel. 215/348-9461;; Doylestown, PA)

Fonthill is the enchanting, reinforced-concrete castle of the archaeologist, antiquarian, and Arts and Crafts leader Henry Mercer. Mercer's Moravian tileworks factory on the same 60-acre property supplied the richly colored, burnished, earthenware tiles embedded as mosaics in the floors, walls, and ceilings of Fonthill. The home is fantastical -- think Arts and Crafts without right angles, with a little Gaud¿ and Mad Hatter thrown in. The home retains Mercer's original furnishings, many of which are built in, and his extensive collection of prints, books, and tiles from China, Persia, Tunisia and, most of all, Delft. The Website photos don't do justice to this extravagantly original dwelling.

Gamble House (tel. 626/793-3334;; Pasadena, CA)

Many consider the Gamble House to be the finest example of the turn-of-the-century Arts and Crafts movement -- with its magnificent mahogany paneling, articulated joinery, exposed structural timbers and shingles, and stained glass windows. For the most part, the house remains as it was designed and built in 1908, by Charles and Henry Greene, of Greene & Greene, for David and Mary Gamble, of Proctor and Gamble fame. The Greene brothers designed the entire place, from the fixtures and furniture to the rugs and lighting, and all the original, handcrafted appointments remain.

Glass House (tel. 202/588-6000; New Canaan, CT)

Since Philip Johnson passed away last January, the postmodern master's 1949 glass home fell into the hands of the National Trust for Historic Preservation. The trust ventures that the house won't be open for tours for at least another year, maybe two, but it's worth putting this one on the list now for a future visit.

Hearst San Simeon State Historical Monument (tel. 800/444-4445;; San Simeon, CA)

In 1919, after inheriting 250,000 acres of land from his parents, publishing mogul William Randolph Hearst said to architect Julia Morgan, "Let's build a little something." Twenty years and 90,080 square feet later, they had the Mediterranean Revival-style Hearst Castle Complex, on a hill overlooking the Pacific Ocean. A number of tour options take visitors through the main house and several outbuildings, encompassing Hearst's impressive art collection, wine cellars, 56 bedrooms, and 61 bathrooms (to give you a sense of the immense scale of the place).

Lyndhurst Gothic (tel. 914/631-4481;; Tarrytown, NY)

The National Trust calls Lyndhurst "America's finest Gothic Revival Mansion." On a 67-acre bluff overlooking the Hudson River, Lyndhurst was built in 1838 by architect Alexander Jackson Davis as a residence half its present size for New York City mayor William Paulding. When merchant George Merritt bought the place in 1864, he worked with Davis to double the home's proportions. In 1880, the mansion ended up in the hands of railroad tycoon Jay Gould, many of whose original furnishings remain. Lyndhurst's magnificent gardens include the first steel-frame conservatory in the U.S.

Taliesin (tel. 480/860-2700;; Spring Green, WI)

Frank Lloyd Wrights' former home -- whose name means "shining brow" in Welsh, for its position on the crest of a hill -- is famously and rightfully known as "the architect's biography in wood and stone." Taliesin was the American master's longest ongoing project, in the works from 1911 until he passed away, in 1959. Wright designed everything on the 600-acre property, from the bric-a-brac in the 37,000 square-foot house and outbuildings, to the ponds and landscaping of the grounds.

If you'd like to explore historic buildings abroad as well, investigate the National Trust's Study Tour program -- trips overseas designed to foster appreciation and understanding of significant architecture abroad. Visit for details.

Talk with fellow Frommer's travelers about historic home tours on our Cultural Immersion Message Boards today.