Few Washingtonians fail to direct their sightseeing, out-of-town guests to the capital city's Embassy Row -- Massachusetts Avenue between Dupont Circle and Wisconsin Avenue NW.

Part of one of the District of Columbia's longest diagonal avenues, this linear gallery of foreign embassies, hotels, churches, clubs and grand homes not only displays unmatched architectural diversity and exuberance, it also can claim to be some of Washington's priciest real estate.

Like most great streets, Embassy Row can be experienced and appreciated in many ways.

It is not a particularly wide avenue. Yet most of its buildings are set back from the sidewalk just enough to make its visual width seem stately without being monumental. Mature oak trees with thick trunks and dense green canopies march rhythmically along each side of the street between curb and sidewalk. They form a natural colonnade that enhances the avenue's stateliness.

Here is a street clearly not intended to carry great volumes of traffic. Indeed, for as long as most people can recall, there always have been annoying traffic jams near the bridge crossing Rock Creek.

Embassy Row is unquestionably unique. The Riggs Bank at Dupont Circle is the last commercial enterprise (not counting hotels) directly visible from Massachusetts Avenue until reaching Spring Valley, a distance of 3 1/2 miles.

The avenue proceeds from Dupont Circle, as L'Enfant intended, straight to Sheridan Circle. It then proceeds along a slightly different alignment straight out to Westmoreland Circle at the D.C.-Maryland line. It deviates from this alignment only briefly when it circumnavigates the Naval Observatory.

Sheridan Circle is one of Washington's smallest but most charming and well-proportioned circles, an intimate urban space simultaneously accommodating architecture, cars, pedestrians and landscapes. Animated by the dynamic statue of Gen. Philip M. Sheridan astride his energetic horse, the circle with its entourage of trees and shrubery is contained beautifully by elegant buildings low in scale but rich in detail.

The architecture along Embassy Row makes Massachusetts Avenue most special. Only by walking, or by driving very slowly (which happens frequently, although usually involuntarily), can you really see all the artifacts and products of nature that contribute to the unique character of this streetscape. From Dupont Circle to Alban Towers at Massachusetts and Wisconsin avenues, architectural time spans almost a century.

The scale of many of Embassy Row's structures lies comfortably between domestic and commercial. Few buildings exceed four stories in height; those that do rarely seem to overwhelm. Elegant, serene, formal, traditional, solid, properly mannered, dignified -- these are some of the adjectives that come to mind when looking at this special street.

The buildings and landscape are, without exception, well maintained. Some buildings are truly unforgettable landmarks in their exquisiteness -- the British Embassy, the Cameroon Chancery, the Cosmos Club, the Society of the Cincinnati, the Indonesian Embassy, to name a few. Only occasionally have latter day architectural lapses occurred, such as the Embassy Row Hotel.

The pattern of development along Massachusetts Avenue beyond Dupont Circle was established at the end of the 19th century and reinforced emphatically during the first two decades of the 20th century. This was the period of mansion building, a period when affluent men, many with newly acquired wealth, thought it fitting and proper to have an appropriate "pied-a -terre" in the nation's capital.

And the place for competitively demonstrating one's economic success, good taste and social standing was along Massachusetts Avenue. Thus many of the mansions and town houses lining the avenue, today flying the flags of the foreign nations who own them, were originally private homes built by turn-of-the-century entrepreneurs. They often hired well-known architects -- Stanford White, Jewels Henri de Sibour, Carrere and Hastings, George Oakley Totten, John Russell Pope -- to express and satisfy their aspirations.

The result was a series of buildings that began stylistically in the Victorian mode with the Blaine House at 20th Street, but then soon became Beaux Arts inspired, Renaissance revivalists for many blocks beyond. Neoclassical, historicist chateaux and palazzos took cues from all over Europe -- France, Italy, Holland, England. Occasionally, Georgian and Queen Anne architecture was revived.

The noblest buildings were fashioned with columned porticos and loggias, rusticated stone bases, pilasters, arches, pediments, carved brackets, elaborate cornices and friezes. Mansard and other roof geometries, sometimes penetrated by dormers, were covered with red and green tiles or gray slate. Roofs were surmounted by balustrades and decorated chimneys that now compete awkwardly with telecommunication antennae.

Wrought iron railings and fences added delicate tracery and transparency at many points, in contrast to the composed opacity of stone and brick wall surfaces.

Farther up the avenue, mansions converted to embassies blend with more recent buildings designed from the outset to be embassies. Stylistic diversity also increases. A few buildings are quite simple, conspicuous by virtue of architectural understatement. They were influenced by the functionalist modernism and stripped classicism of the 1930s, '40s and '50s.

The Islamic Center, with its distinctive minaret and moorish outlines, marks the approach to the bridge across Rock Creek Park, a verdant, topographically dramatic interlude if you can take the time to watch the landscape instead of the traffic.

Beyond the bridge appears Brazil's chancery and inscrutable, pristine, black glass box perched daringly atop a deeply recessed masonry base. A small concrete pyramid identifies the building, its cantilevered abstractness grabbing attention away from John Russell Pope's 1931 palazzo serving as the Brazilian Embassy.

Just south of Observatory Circle is the landmark British Embassy, architect Sir Edward Lutyens' palladian-inspired, winged-brick building erected in 1931. Joined to it 30 years later was an unpretentious modernist hancery structure that parallels the avenue. The original embassy looks undeniably ambassadorial with its fenced and gated forecourt, its multiple facade and massing symmetries and its classical entry portico.

Finally, after skirting the circle, Embassy Row ends with what may seem to be the more sacred high ground of Massachusetts Avenue. Three distinctive churches -- St. Nicholas Cathedral (Russian Orthodox), Byzantine-styled St. Sophia (Greek Orthodox) and the gothic National Cathedral -- help claim this territory, even though none front directly on the avenue.

Everything adds up visually along most of Embassy Row -- the architecture, the lawns and courtyards, the majestic trees and colorful shrubbery, the walls and fences. It's an ensemble street that imparts a holistic and memorable impression. Yet each of its constituent elements, each of its distinctive buildings, has a rich life of its own.

Of course, one shouldn't forget that it took lots of capital to create, preserve and maintain Massachusetts Avenue. But design talent, architectural traditions, and a collectively understood commitment to high aesthetic standards were the real keys to giving Embassy Row its form and character.

NEXT: Building Big.