The pharaohs had the Pyramids. America's rulers, as biographer Robert Caro once observed, have the presidential libraries.

The styles of these shrines run the gamut, from comfy vernacular (Franklin D. Roosevelt in Hyde Park, N.Y.) to mausoleum modern (Lyndon B. Johnson in Austin, Texas). For years, the John F. Kennedy Library in Boston, its dark prism of glass set against a chalk-white tower, has been the most architecturally ambitious, a monument with a capital "M" that looked as imposing and indestructible as the Pyramids.

The William J. Clinton Presidential Center, which will be dedicated here Thursday, offers a bracingly different model: a bridgelike building that shoots into space, simultaneously striking up a conversation with an old railroad bridge beside it and evoking Clinton's metaphorical

Bridge to the 21st Century." The design suggests possibility, not finality; motion, not repose; transparency, not impenetrability. Its upbeat modernity seems wholly appropriate for a president whose tenure witnessed the emergence of key aspects of contemporary life, from widespread computer use to a full-fledged global economy.

Designed by James Stewart Polshek and Richard Olcott of New York City's Polshek Partnership Architects, the Clinton Presidential Center also was shaped by Clinton himself, a famously hands-on president. He didn't want a Frank Gehry eruption of metal. He wanted something all his own. And now he's got it, even if his library is like all the others in downplaying presidential foibles and fumbles, most notably the impeachment that resulted from Clinton's affair with White House intern Monica Lewinsky. Don't expect to see a certain blue Gap dress. It has been ever thus: There is an inevitable tension in presidential libraries between history and hagiography.

Built for a privately raised $165 million and occupying a riverfront site that the city of Little Rock donated for another $11 million, the Clinton library is the latest in the nation's coast-to-coast chain of presidential libraries. The first, FDR's fieldstone-clad Dutch Colonial library in the Hudson River Valley, opened in 1941 and was designed by Roosevelt himself. It began the custom of building public storehouses for presidential papers, which previously were thought of as private property to be stored, destroyed or sold to autograph hounds. Clinton's has the most material of the libraries -- 80 million pieces of paper, 1.5 million photographs and 79,000 museum objects, including the sunglasses he wore when he played the saxophone on "The Arsenio Hall Show."

It is not, strictly speaking, just a library, but rather (shades of the Imperial Presidency) a "Presidential Center" that consists of three main parts: the five-story main building, which is more a museum than a library; a partly submerged archives building, where the vast majority of the documents are kept; and a handsomely restored Beaux-Arts railroad station that houses the University of Arkansas' Clinton School of Public Service. Together, this trio makes a serene, campuslike precinct, meant for presidential scholars, students, journalists and, of course, tourists.

At first glance, Little Rock and tourism would seem to have as much in common as Chicago and pleasant winters, but the small state capital (population 183,000) holds some surprises. A few blocks to the west of the Clinton library, across the steel and asphalt barrier of heavily traveled Interstate Highway 30, is Little Rock's surprisingly urbane River Market District, where old brick buildings have been turned into bars and restaurants, parks and amphitheaters line the river, and an old yellow trolley rumbles along President Clinton Avenue. There are threads of city living here, and the library's enlightened idea is to weave those threads into a bigger urban cloth.

A resounding victory

In that respect, the library is a thumping success, having helped to draw an impressive $1 billion in real estate investment to downtown Little Rock. Just behind the library, for example, the structural framework is now in place for what will become the headquarters of Heifer International, a non-profit world hunger organization. In addition, the library's 30-acre site includes handsome contemporary parkland by Hargreaves Associates of Cambridge, Mass., extending Little Rock's chain of riverfront parks.

But it is one thing to spark an urban renewal and another to produce a memorable work of architecture, and that is where the Clinton library distinguishes itself. It rises above the imperfect standard set by the 25-year-old Kennedy Library, which was designed by New York City architect I.M. Pei and was, Polshek confides, Clinton's favorite presidential library.

For all its geometric power, Pei's library is not elegantly detailed and seems dropped onto its barren site, several miles south of downtown Boston, where there is little but Boston Harbor to relate to. Polshek's library, on the other hand, is expertly woven into a site that is rich in context, from a gracefully arching Rock Island Railroad bridge that springs across the Arkansas River to the river itself, a wide, sometimes brown, takin'-its-own-time waterway.

Polshek, an Akron native, has long been adept at what might be called "narrative modernism," infusing the abstract forms of modern architecture with the capacity to tell a story. The best example is his Rose Center for Earth and Space in New York City, completed in 2000 and consisting of a giant off-white sphere that seems to levitate within a transparent glass cube. He has done it again in Little Rock. Critics who once carped that the museum resembled a trailer on stilts should now be in full retreat.

Like the Rose Center, the Clinton library seems fresh but inevitable. Its museum is a simple rectangular volume based on a state-of-the-art update of a tried-and-true structure, the diagonal truss. The truss immediately relates the building to the nearby bridges, yet it is no facile, retro move. The design is imbued with the dynamism of contemporary life. The cantilevered box appears perched on its off-center entrance, making it look as if it might swivel around like the boom of a construction crane. But no crane is this architecturally refined.

At first, the architects acknowledge, they did the obvious thing, placing the building parallel to the river to maximize views of the water. But they quickly realized such a placement would point visitors toward a scruffy waterfront and run-down houses across the river. Not very presidential.

By turning the building 90 degrees, as if it were one of the hands of a clock, the architects at once downplayed this view and directed the visitor's gaze up the river -- toward six bridges, especially the long-closed Rock Island Railroad bridge, which is eventually supposed to reopen as a pedestrian bridge that will be part of the Clinton library. The six bridges, Olcott says, are the "leitmotif of Little Rock."

The museum building is thrillingly bridgelike, its upper floors cantilevering off its beefy steel columns. At one point, they span a jaw-dropping 150 feet. Yet the cantilevers are not exhibitionistic. They allow the new riverfront parkland to pass beneath the building, expressing, as Polshek says, Clinton's passionate environmentalism.

Like all good architecture, the museum building grows in richness as you approach and assimilate it. From the River Market District, you are beckoned by one of the big rectangles sliced into its facade. Closer up, you notice the tic-tac-toe grid of light-green glass panels that are held in place by steel fittings that resemble spiders' legs. The glass doubles as a sunscreen and the outer wall of an airy veranda that wraps around the building, a climate-sensitive, Southern-fried touch that further differentiates the museum from the old Little Rock bridges.

Polshek and Olcott have sculpted the museum's underside with aluminum shaped like an ocean liner's hull, hiding unsightly mechanical equipment and suggesting the belly of a whale -- or maybe the ship of state. The lone weakness comes at the museum's top, where an early plan for a smokestack-like oval that expressed oval rooms inside was replaced by a boxy (and far less graceful) roof. Still, the outside sings.

The interior is also quite special, in no small part because Clinton was such an attentive client. He insisted, for example, that the museum's replica of the Oval Office be placed so its windows would let in natural light. When the designers proposed a variety of plans for the exhibition space, he chose the one that reminded him of the library at Trinity College in Dublin, a two-story room with a soaring barrel vault and columns lined with bookshelves.

Visitors to the museum will enter a sleek ground-floor lobby and head upstairs, where they will be greeted by a striking view of downtown Little Rock out of one of those rectangle-shaped cutouts. Moving toward the river, they'll pass through a replica of the White House Cabinet Room and then enter the museum proper.

There, pairs of two-story cherry wood "pylons" march along the main aisle like the columns of a Gothic church. Between each pair, on each side of the aisle, is an alcovelike space that covers some aspect of the Clinton administration--on the first level, from the economy to health care; on the second, from life in the White House to Clinton family pets such as Socks the cat. The visit ends at a full-scale replica of the Oval Office.

A matter of proportions

Even if the museum merely evokes a library rather than being the real thing, it dazzles with its fine proportions, warm materials and animating natural light--a sharp contrast from the windowless "black box" of the typical presidential library.

Polshek and the exhibition designers, the New York City firm of Ralph Appelbaum Associates of New York City, devised a space that gets filtered light, allowing objects to be displayed without harm. The setup also permits the building's handsome trusses to remain visible from the interior, maintaining continuity between inside and outside.

If the museum's processional, church-like layout makes it feel like the Shrine of Slick Willie, well, that's simply the nature of presidential libraries. We go there to pay homage not only to a given president but also to the institution of the presidency. Triumphalism reigns, even in a museum that has to come to terms, however glancingly, with the subject of impeachment.

The museum, it turns out, is as skilled at "compartmentalizing" the subject of Clinton's impeachment as Clinton was while he was in office. The exhibition space mentions impeachment, but hardly emphasizes it, restricting the hugely controversial matter to a single alcove on the museum's first level. The alcove also covers the political battles leading up to impeachment, further deemphasizing it. Tiptoeing has never spoken so loudly. Only history will be able to judge whether the museum's take on impeachment is too little or just right.

For now, this much is clear: The Clinton Presidential Center is a major design success. It breaks the mold of the presidential library even as it builds an extraordinary bridge between past and present, architectural object and urban context. Here, monumental modernism is liberating, not oppressive. The monument to the ruler also benefits the people. Whatever your politics, red state or blue, that ought to be a blueprint for a better presidential library.