A house for humans.

WHETHER descending the ramp of the old Guggenheim or struggling up the ramp of the new, one feels like a cross between Sisyphus and a pinball. Frank Lloyd Wright's masterpiece may indeed be a joy to look at, but it is hell to inhabit: the spiraling rotundity of the main structure wearies the limbs as it baffles the mind. Notwithstanding its much publicized reopening after two years of expansion and renovation, the Guggenheim remains entirely unsuited to our species in the present state of evolution.

On the outside all is well enough. The original museum, which had entered its fourth decade looking somewhat frowzy, is once again pristine. A new building, designed by Gwathmey, Siegel and Associates, rises up beside it, with cream-colored surfaces patterned into a delicately detailed grid. If anything, by concealing the buildings behind the museum, this new ensemble creates a more satisfying resolution than before.

If architecture, like sculpture, had only to occupy space rather than to contain it for human use, no one could deny the success of either building. But architecture is required to do more. Wright's interior, confusing to begin with, has just become several times more so. Heretofore you only had to contend with that punishing spiral, partially mitigated by three horizontal spaces along the way. Now the adjoining spaces proliferate and spoil the manic single-mindedness of Wright's plan. And while it is surely good that more of the museum's extensive holdings can be displayed to the public, the new low-ceilinged spaces are ill-suited to their purpose. They are somber on even the brightest days, and each floor has at least one narrow loop where the guards have to direct traffic lest visitors harm one another in passing.

Perhaps the best that can be said for these new galleries is that you may never find them. Such is the wooziness of Wright's structure that some of the larger rooms remain empty, their existence unsuspected, while tiny siderooms fill up with people who have no idea of the smallness of the space they are about to enter. And once inside it is too late: others, in similar ignorance, are pressing from behind and there will be a fight to get out.

There is a right way and a wrong way to do things, and if Louis Kahn, the subject of an ambitious exhibition at the Museum of Modern Art, had designed the Guggenheim, everything would have turned out better, if less dramatically. The younger man would never have sacrificed comfort to style. "I teach appropriateness. I don't teach anything else," Kahn told his students at Yale. Though the generations of Wright and Kahn were separated by that long, lugubrious, postwar shadow of the International Style, with its characterless boxes of steel and glass, the two men were allied in the belief that architecture ought to be about something nobler.

They arrived at this conviction from opposite directions. In Wright's style, which had grown out of Art Nouveau early in the century, there was a determinedly Yankee individualism. Louis Kahn, on the other hand, born in Estonia to Jewish parents in 1901, worked for many years under the influence of Le Corbusier and Mies van der Rohe. Only around 1950 did he realize that something was missing from architecture that had to be put back. Kahn once fell out of bed, he claimed, with the realization that "assembly is of a transcendent nature. Men came to assemble to touch the spirit of commonness." This and similarly vaporous principles would inspire a humanizing option for those who had grown sick of the rigidity of the International Style. It is largely Kahn whom we have to thank for showing us the way out of that Miesian trap into which architecture had fallen.

This he accomplished by revolutionizing our expectations about space and layout, about massing, and about materials. Kahn's Yale University Art Gallery, his first really big commission (1951-53), is a staid box, beautiful, but still fully obedient to Mies. There is no feeling of uniqueness to the structure, of its specific monumental purpose. Only the stairwell, its cylindrical mass capped by a floating, triangulated dome, presages the inventiveness to come. Soon you see something new happening in the Richards Medical Research Building at the University of Pennsylvania, where Mies's rectangular box has been fractured into so many semi-autonomous facets. At the Salk Institute in La Jolla, California, two phalanxes of discrete pavilions confront one another against the backdrop of the Pacific Ocean. The interior of the library at Phillips-Exeter Academy reveals the book stacks through walls perforated by four massive oculi, topped by a dome that recalls the Roman Baroque structures of Borromini.

Kahn effected a similar change in notions of massing. One of the first postwar architects to reintroduce historicism, he created Gothic buttresses for the First Unitarian Church in Rochester, New York. In Dhaka, Bangladesh, massive turrets are strung along the Ganges, while the main structures of the city resemble something between a mosque and a fortress. All these forms are strikingly, resolutely modern in their lack of ornament, and at the same time resonant of the living past. Their echoes and allusions are further enhanced by the materials Kahn used. It was in the courtyard of the Salk Institute that poured concrete achieved, for the first time, the delicacy of tooled leather and the warmth of alabaster.

These structures, like so many other works by Kahn, bear out his words: "I teach appropriateness." There is a humility and a humanity to them that suit each work to its specific site and its specific purpose, without, however, concealing the individual, unmistakable stamp of the author.