Frank Lloyd Wright's Fallingwater (above), Kentuck Knob and Duncan House can all be seen in a daytrip from Pittsburgh. The famously zen Fallingwater, which inspired Ayn Rand's classic novel The Fountainhead and recently underwent a $5 million restoration, is a cantilevered structure that sits partially atop a stone waterfall in the middle of the woods. The water passes underneath, which helps the structure blend with its natural surroundings. It was voted "the best all-time work of American architecture" in 1991 by the members of the American Institute of Architects.

There are plenty of designs by Finnish architect Alvar Aalto in his homeland, including large public buildings like Finlandia Hall (above) in Helsinki and smaller residences like Aalto's summer house, Villa Mairea, in Noormarkku. The Paimio Sanatorium was built originally as a TB ward. Aalto's "gesamtkunstwerk" approach to this project involved all of the building's accessories (furniture, facilities) being designed to fit together. The building was converted into a general hospital in the '60s, and remains a part of the University of Turku Central Hospital.

Dessau was the second home to the Bauhaus arts school in Germany, and, as a result, has quite a few examples of classic architectural modernism. The Bauhaus Building itself was designed by Walter Gropius (who taught at the school) to specifically attend to the needs of the artists and designers who would be working there. The building reflects the Modernism's International Style and exemplifies Gropius's futuristic ideas, which called for "an architecture adapted to our world of machines, radios and fast cars." The Bauhaus Masters' Houses, also designed by Gropius, were built to house permanent Bauhaus teachers like Paul Klee, Wassily Kandinsky and Gropius himself; they were constructed using industrial, prefabricated elements and feature glass fronts and large studio spaces.

Founded in 1909, Tel Aviv sprung more or less out of the sand dunes as a Jewish colony separate from nearby Jaffa. As it grew, a master plan was developed for the city by Patrick Geddes, and in the '30s Tel Aviv attracted architects from around the world to meet the booming need for new housing, quickly becoming a major center for European International Style. Today there are more than 4,000 buildings built in this style. Buildings in the area known as the White City were designed along Bauhaus principles of functionality and simplicity as adapted to the hot Mediterranean climate. As the name suggests, all of the buildings are white to reflect the sun, and buildings are designed to maximize the effect of cooling breezes.

Chicago has long been a major destination for tourists interested in architectural modernism. In the early part of the 20th century, European architects traveled to the Midwest to see Chicago's distinctly American take on building design (particularly its skyscrapers). Frank Lloyd Wright's Robie House, built almost 100 years ago, is known as one of the masterpieces of the "Prairie" style. It's in the midst of a restoration, but there are still several tours daily. The Illinois Institute of Technology has an innovative new campus center by Rem Koolhaas. And 58 miles outside of the city, in Plano, Ill., Mies van der Rohe's beautifully spare, steel-and-glass Farnsworth House (above) stands on stilts by the water.

After the partition of India and Pakistan in 1947, the Indian state of Punjab needed a new capital to replace Lahore, which had become part of Pakistan. It was decided that a new city should be designed (in the words of prime minister Jawaharlal Nehru) "unfettered by the traditions of the past, a symbol of the nation's faith in the future." The project was eventually realized in the designs of Swiss-born architect Le Corbusier in the '50s. Chandigarh was designed on a grid pattern with sectors of identical size creating rectangular neighborhoods—each with their own markets, schools and temples—all within walking distance of the city's center. The buildings are made of exposed brick and stone with rough surfaces, and set among landscapes and greenery. The city as a whole is a wonder of urban planning, but Le Corbusier's major buildings include the Court House, the Assembly, the Museum and Art Gallery and the School of Art.

The desert oasis of Palm Springs has plenty of classic examples of Mid-Century modernist architecture. Representative homes and public buildings throughout the Coachella Valley by Albert Frey, Richard Neutra, Donald Wexler, E. Stewart Williams and William Cody can all be visited in a day trip. The Kaufmann Desert House (above), one of Richard Neutra's most famous buildings, was built for the same Kaufmann family that commissioned Fallingwater; in May, it nearly sold for $19 million. (It's now back on the market.) The house has a series of horizontal planes and floor-to-ceiling windows that give an unobstructed view of the desert and mountains. Williams designed residential and commercial buildings throughout the area, including Twin Palms, built as Frank Sinatra's original desert estate—which you can rent for $2,600 per night. Many other notable Frey works are here, too, including Palm Springs City Hall, Frey House II, and the Loewy House.

Barcelona is particularly known for the architecture of Antoni Gaudi, whose work falls into the category of Art Nouveau, rather than modern. His ornate Sagrada Familia church (construction on which began in 1882 and won't be finished for decades more) and biomorphic Casa Mila (above) are must-see sights on any architectural tour of the city. But Mies van der Rohe's minimalist Barcelona Pavilion, originally designed to house the German delegation at the 1929 International Exhibition, is a true classic of modernism. The building has a simple design, with a podium in front of a reflecting pool, but was built incongruously from extravagant materials including Roman travertine marble and golden onyx.

Soon after Juscelino Kubitschek assumed Brazil's presidency in 1956, he contacted architect Oscar Niemeyer and asked him to develop a proposal to build a new capital in a barren patch of land hundreds of miles from any other city. Niemeyer and Lúcio Costa executed that vision, creating Brasilia from scratch with a unified design through its city center and an underlying socialist ideology (all apartments are rented by the government, and the homes of common workers share the same buildings as top government ministers). The city was built and dedicated within four years. Brasilia, as a whole, is listed as a World Heritage site by UNESCO; buildings of particular note include the Palácio da Alvorada, Palácio do Planalto, Cultural Complex of the Republic, Cathedral of Brasília, and Praça dos Três Poderes.

Los Angeles has quite a few modernist sites of note, and many classic structures like the Avalon in Beverly Hills and the Standard (above) in Hollywood—both hotels—are worth a visit. But some of the best examples of modernism can be found among the Case Study Houses, which were built as a project sponsored by the journal Arts and Architecture. Located in the Pacific Palisades, the Eames House, built by Charles and Ray Eames, is one of the best known of these. The Eameses used standard industrially made components to make an artistic home and studio. The exterior of the house is a pattern of panels made of wood, glass, aluminum and wired plastic of various colors. Frank Lloyd Wright's Barnsdall Residence (also known as the Hollyhock House) is another classic, using concrete blocks to explore the interplay of indoor and outdoor living.