If you're mesmerized by the curves of Art Nouveau, the sleekness of Art Deco, by ancient Roman arches or even by distinctive Gothic peaks, www.independenttraveler.com has compiled for architecture buffs a small, thoughtful selection of cities with unforgettable buildings and monuments. Check www.greatbuildings.com to locate the world's finest examples before planning your travel itinerary. Here is an edited selection of entrancing cities you absolutely must visit before you die.

Istanbul, Turkey: Straddling two continents and inarguably one of the planet's most exquisite cities, the former Constantinople is architecturally unique because of its extensive Christian and Islamic histories. The influences of both major religions are evident in the city's fascinating jumble of Roman, Byzantine and Ottoman edifices. Mosques — many of which were converted from Christian churches — comprise a large part of Istanbul's celebrated architecture. The sixth-century Hagia Sophia was for many centuries the largest church in the world until it was converted into a mosque. With a mammoth central dome, 182 feet tall and 102 feet wide, it is considered an ideal of Byzantine architecture. Huge, 17th-century Sultan Ahmed Mosque with its soaring minarets, better known as the Blue Mosque, is an oft-photographed icon of Istanbul from the classical Ottoman period.

In addition to its many mosques, Istanbul is bursting with imposing secular architectural treasures. Travelers always head for beautiful Topkapi Palace, seat of the Ottoman Empire for nearly 400 years. This complex, which once housed 4,000 members of the sultan's household, encompasses four main courtyards flanked by dozens of buildings and gardens. Now a museum, the palace is notable for its harem, priceless jewels, gem-encrusted thrones and other resplendent examples of royal excess.

Barcelona, Spain: This Catalan city is a sprawling compendium of 2,000 years of impressive European architectural styles, from Roman, Gothic and Baroque to Victorian and the unique Art Nouveau (or Modernisme) of Antoni Gaudi. This early 20th-century style is characterized by whimsical curves, unexpected asymmetry and flamboyant colors. Gaudi's best-known completed work includes Casa Batlló and Casa Mila — multistoried buildings seemingly designed without a single straight line. The architect's most famous structure is the still unfinished Sagrada Familia cathedral, a fanciful pastiche of spindly towers with a geometric interior and a sculpted, frothy facade.

Beijing: This capital city boasts scores of palaces, temples and other structures that are emblematic of traditional East Asian architectural movements built before Western influences began to shape the city. Top draws include the Great Wall, constructed from the 5th to 16th centuries and stretching nearly 4,000 miles; the immense Forbidden City, Beijing's imperial palace whose 980 buildings epitomize Chinese palatial architecture; and the 15th-century Temple of Heaven, a Ming-period sacrificial altar that was intended to create a meeting place between heaven and earth. Its photogenic Hall of Prayer for Good Harvests is formed of an amazing circular structure made entirely of wood and secured without nails.

Chicago: Closer to home, the Windy City is famed for a quintessentially American structure — the skyscraper. Its most famous example is 110-story Sears Tower, the tallest building in the world until the late 1990s. Other noteworthy skyscrapers include 311 South Wacker Drive with its brightly lit Gothic-style top and the towering Aon Center, covered with 43,000 slabs of Italian marble.

And, of course, an architectural examination of Chicago would not be complete without viewing the work of Frank Lloyd Wright, who began his career here. Pilgrimage must-sees cover the Frank Lloyd Wright Home and Studio; the Oak Park neighborhood, graced by more than 20 privately owned Wright houses; the echoing interiors of Robie House; and the modern angles of the Charnley-Persky House. For information on the master and his work, investigate the Frank Lloyd Wright PreservationTrust at www.wrightplus.org.

Buenos Aires, Argentina: This sophisticated, European-flavored capital has grown around plazas and neighborhoods, each with colorful, individual architectural styles. You'll find elaborate Art Nouveau mansions, Baroque and Neoclassical cathedrals, handsome colonial public structures, sleek Art Deco apartment buildings and more. Deemed the city's top architectural triumphs are the dazzling interiors of the French Renaissance-style Teatro Colon and Casa Rosada, the pink 16th-century Neo-Renaissance Presidential Palace whose balcony was immortalized by the messianic appearances of former first lady Eva Peron.

Rome: Once the greatest empire on earth, Rome retains many of its early Christian monuments, medieval palaces, Baroque fountains and cathedrals and other masterpieces built according to almost every Western architectural movement of the last 2,000 years. A mouthwatering feast for the architecture aficionado. At the head of any A-list would be the first-century eliptical amphitheater of the Colosseum; Roman aqueducts — marvels of ancient engineering that revolutionized urban life in the known world; and Vatican City's magnificent St. Peter's Basilica, largest cathedral on earth. Other premier architectural cities among my personal favorites are Moscow and St. Petersburg, Russia; Paris; San Miguel de Allende, Mexico; Quebec, Canada; and Charleston, S.C.

Irene Croft Jr. of Kailua, Kona, is a travel writer and 40-year veteran globetrotter. Her column is published in this section every other week.