A ROUTINE drive down Georgia Avenue, past the barbershop storefronts and the Caribbean cafe's, inevitably reveals the all-too-brief silhouette of the most prestigious black educational institution in the country -- some would say, in the world.

It is here on the sloping main campus of Howard University that former Cabinet member Patricia R. Harris pledged a sorority, Atlanta Mayor Andrew Young signed up for the swim team and Supreme Court Justice Thurgood Marshall pored over his torts.

You won't find any trumpeting gateway marking the entrance and, from the Georgia Avenue side, you may not be able to distinguish neighborhood buildings from the university proper. But once on the campus' well-manicured hub, known colloquially as "The Yard," you will find Howard a stately, if not strangely secluded, oasis along the edge of Washington's neglected Shaw sector.

Howard and its adjacent communities are a study in the dichotomy of black America: In one block, boarded up storefronts stand as testimony to the frustration of the 1968 riots, while in the next block, PhD candidates fiercely debate "the effects of trace metal contaminants on immunology responses . . ."

This is a decidedly high-minded institution -- clearly secure in its status as the archetypal "capstone of Negro education," a phrase coined by the university's eighth president, John Gordon, in 1904 and still tossed about in glossy brochures and at annual convocation rituals. Within the past five years, seven heads of state, President Reagan, Vice President Bush, Sen. Edward Kennedy and singer Stevie Wonder, among others, have all visited Howard to speak or either receive or bestow awards.

University officaldom quickly touts the names of familiar entries in the current Black Who's Who catalogue, noting that a majority are Howard alumni: actress Roxie Roker of "The Jeffersons," dancer/actress Debbie Allen of "Fame," former senator Edward Brooke, novelist Toni Morrison, director Ossie Davis, half of the nation's black physicians, dentists and engineers, thousands of "first-black this or that."

A little history before the sights:

Founded originally as a "normal school" for newly freed slaves, the university was chartered in 1867, enacted by Congress, approved by President Andrew Johnson, and named for Gen. Otis H. Howard, then commissioner of the Freedmen's Bureau. Almost since its inception, Howard has been a line item in the federal budget, the only private university to receive annual appropriations from Congress.

An average of 12,000 students from all 50 states and more than 80 foreign countries converge on Howard in any given year, most of them shuttling between classes on the 75-acre main campus just off Georgia Avenue.

They sit through seminars on "The Black Diaspora" or lectures on "Monetary Analysis" in (abolitionist) Frederick Douglass Hall, read Shakespeare and Plato in (philosopher) Alain Locke Hall, and sleep/study/wash/play in dormitories such as (medical researcher) Charles Drew Hall for men or (underground railroad conductor) Harriet Tubman Quadrangle for women.

Clearly, a walk through campus is a stroll down black history's memory lane. But, in recent years, as peak enrollment forces expansion, a stroll through campus has become more of a hike. With 17 schools and colleges, dozens of institutes and research centers, a hospital, radio station, television station and hotel, the Howard name is etched on satellite offices all over the city.

The law school, for example, juts out of the velvet-green landscape of the 22-acre Dunbarton Campus west of Rock Creek Park, while the veterinary research center is quartered in the 108-acre Beltsville campus in Prince George's County. Even now, pockets of the cramped main campus have become a mesh of steel and scaffolding as construction crews erect a new business school on Georgia Avenue and an undergraduate library on the Fourth Street boundary.

From the top floor of the campus' oldest structure -- the red, chipped Victorian mansion on the hilltop where Gen. Howard once lived -- you can get a postcard view of Washington clear to the monument. In the basement of the newest building -- the sleek, glass-and-concrete University Center -- you can zap Pac Man's enemy obstructers until your thumbs turn blue.

But neither can compete with "Founders." Nearly every poster, yearbook, catalogue, flyer, program, pamphlet or logo will flaunt a photograph, painting or etch of the unmistakable Founders Library. It is a classic collegiate structure complete with steeple and Roman-numeral clock -- a Howard signature, a campus landmark, and a place to study.

More immediate needs and official business are tended to in the "A" building ("A" for administration), the lofty 1950s-ish headquarters of Howard's powers that be. In 1968, when students' demands for "a more relevant curriculum" weren't met, 800 students seized the "A" building," shutting down the school for five days.

Howard's very first classroom building -- a tiny wood-framed job, perfect for the university's initial enrollment of four -- was an abandoned German dance hall and beer saloon on Georgia Avenue. Now, on that same lot, a $53 million, 486-bed hospital stands in its place.

Its predecessor, Freedmen's Hospital, now serves as the School of Communications and as the office of WHMM, the university's public television station, for which Howard flew in comedian Bill Cosby to emcee the station's $50,000 birthday bash last year. WHMM's sister station, WHUR-FM, with the number-one evening radio show in the area, is tucked away on the side of the football field in a tiny, two-story structure, affectionately called "Tempo C."

Just north of the Texaco station back on Georgia Avenue, stands the Howard Inn -- the Harambee House Hotel "Howardized" with a completely refurbished interior. The university bought the hotel last year for $1.3 million for its hotel management courses and put $500,000 into neo-art renovations.

As for entertainment diversions, the dozen or so fraternities and sororities and a number of close-knit state clubs are usually sponsoring something, from wine-and-cheese coffeehouses to 24-hour dance marathons.

Then there's always the University Center: fashion shows, discos, luncheons, dinners, concession stands, bake sales, practically everything is held in the center. For students, this is the campus hangout.

A note on Fridays:

As long as the sun's out, it's the day the Greeks line up to strut their elaborate formation-style steps. Noontime, and The Yard is packed with onlookers cramming to catch a glimpse of them stomping and chanting their fraternal rituals, feeling the kind of electricity and oneness that testifies to the Howard experience. Truly a must-see occasion