Though I have seen the vision at least a hundred times in the last 10 years, it never fails to surprise. Many Washingtonians must have had the experience: Traveling fast in a car, heading west up a hill on a particularly treacherous section of the Capital Beltway in Montgomery County and, cresting the hill, being astonished yet again by the sudden apparition rising splendidly from the ridge of trees below -- the Mormon Temple.

When viewed from a car speeding in the opposite direction, the shining white monument seems not nearly so massive, but this perspective, too, is a surprising one. And even more dangerous. It takes some experience to maneuver the beltway while sneaking glimpses at the almost dematerialized form of the temple, with its six golden spires and the Angel Moroni all peaking crazily through and above the trees in a dizzying spectacle.

The Mormon Temple was a spectacular landmark even before being formally dedicated on Nov. 19, 1974, and it has, I think, improved with age, as we have stored and categorized our collective impressions of it: the autumn-sun, winter-night, spring-rain, summer-haze, morning-smog or sunset-pink views -- the list could go on. Neither Great Architecture nor High Art, it is an almost bizarre combination of sophistication and sincerity, knowledgeability and naivete'. Above all, it is a memorable and likable building.

There is, clearly, not even an ounce of humility in the way the temple presents itself to the world. As chief design architect Keith Wilcox recalls in "A Personal Testimony: Concerning the Washington Temple," an account of the building from conception through construction, the potential "missionary impact" of the structure was high on the minds of the church fathers when they selected the prominent suburban site early in the 1960s and when, later in the decade, they commissioned its design from a group of Mormon architects. They wanted a building that would, no mistake, stand out.

Church leaders, Wilcox recounts, "had traveled to the East Coast and had interviewed several nationally known architects" for the job, but "had become discouraged in attempting to explain the function of a temple to these non-Mormon architects." Initially the Mormon designers worked independently of one another, coming together to see the project through only after Wilcox's design had been singled out. He visualized the basic points of the design -- a six-sided building with six towers, one slightly higher than the others -- in a single night of intense, almost trancelike work during which he felt that "a power beyond my own gave me strength."

In his recollections Wilcox stresses the symbolic importance of a design based on multiples of three, like so many facets of Mormon theology and organization, and though later altered -- the hexagonal plan envisioned by Wilcox was stretched out on two sides and interior arrangements were shifted -- the design remained true to his initial concept in all fundamental respects. That brief period of sharp, revelatory creativity, which minus its specific religious connotations is similar to incidents recorded by many artists, certainly helps to account for the clarion clarity of the building's final image.

Of course, most of us would not recognize the Mormon symbolism of the temple without being told about it. What we can see in the building without help are recollections of ancient white temples on high hills ("This temple, like all temples, should have a certain timeless quality," Wilcox wrote that first night), of soaring church steeples, of cathedrals towering above medieval cities, of fantasy castles on mountaintops (King Ludwig's castle at Neuschwanstein, the vertical Victorian wedding cake in the Bavarian Alps, comes to mind), of 1920s New York skyscrapers with their setback profiles, of dreamy Moderne movie sets -- above all the Emerald City, here white, of Oz. Some of these associations are inescapably ironic. Because of the way the temple commands its hillside site, it is impossible not to think of it functioning as what Germans aptly call the Stadtkrone, or city crown, in the manner of the great cathedrals of the Middle Ages. Yet nothing could be further from the fact: The temple, surrounded by a beautifully planted parking lot, is a thoroughly suburban building. Furthermore, because on the day of its dedication a decade ago it was closed forever to non-members of the Church of Jesus Christ of Latter-day Saints, the building is in no way the functioning centerpiece of its immediate neighborhood. To the contrary, the temple, ministering to a widely dispersed flock that arrives in cars, necessarily sets itself apart.

The temple confounds conventional expections on the inside, too. Approximately half a million people took advantage of the Mormons' invitation, before the dedication, to tour the nearly finished structure. Many may have been surprised, as I was, not to find on the inside the great sanctuary space traditional in Christian cathedrals. After all, from the outside the building suggests a soaring interior room.

In actuality, the interior is much like a six-story office building. In conformance with the Mormons' liturgical and social needs, the temple contains sealing (or marriage) rooms, ordinance (or teaching) rooms, locker rooms and laundries (to accommodate the change from street clothing into religious apparel), and a variety of rooms for social activities (kitchen and cafeteria, a children's area) and offices. (The division into six floors was, again, part of Wilcox's original inspiration.)

There are indeed several special chambers of more than average presence and height -- the baptismal font, the celestial room, the solemn assembly room -- but in general the interior architecture is undistinguished, and the appointments, to judge from a video presentation at the Visitors' Center, run a somewhat depressing gamut from motel modern to hotel rococo. The only spaces to excite the architectural imagination are those of matching stairwells, with their stained-glass corners, running full height in two of the six towers.

The civic importance of the Mormon Temple resides, then, almost entirely in its exterior -- in the respectful if emphatic way it dominates its site and controls the beltway vista, in its sculptural qualities and, especially, in the romantic richness of its imagery. The design was ahead of its time in its concern with image, allusiveness and communication, and this helps to explain why the building is popular despite the opinions of some architects and other guardians of taste, who have been known to dismiss the temple with a shrug and an elouent rolling of the eyes.

Ten years ago I found the building odd, and I still do. The difference is that today I see it as an inspired sort of oddness. The beltway temple, at once a very Mormon and very American building, is without question an unforgettable holy house.