None the worse for wear, the modest Alvar Aalto exhibition that opened here at the American Institute of Architects in 1963, has returned after 17 years of travel.

This is surely a record of some kind. But while G. E. Kidder Smith's exhibit panels of 20 of the Finnish architect's more famous buildings are in pristine condition, age has not improved the exhibition. As happens with wine at times, the show has soured a little.

This is not to say that Alvar Aalto has soured. Quite to the contrary. Ever since his death in 1976, his reputation among architecture buffs has risen from that of "one of the leaders of the modern movement" to that of the hero who bolted the movement or, at any rate, stood above it.

Aalto is now an architectural superstar, who always acknowledged the imperatives of historic and regional tradition and never doubted that buildings must be designed for people. Aalto, in short, is a posthumous Post-Modernist.

If genius can be labeled at all, this is not altogether wrong. But poor Aalto, who was a fun-loving Finn and never saw himself as an international guru, let alone a wine-and-cheese party idol, was neither Modern nor Post-Modern. He did as circumstances dictated.

His overriding circumstance was Finland.

Finland is cold for the better part of the year and no place for glass boxes or flimsy slabs or stilts. Finland has no steel but an abundance of trees and clay. Finland's monochrome snowscape is no place for colorless, unadorned, bare, square buildings. Can you imagine a Seagram Building in the center of Helsinki?

And Finland, which became an independent nation only in 1916, when Aalto was in architecture school, has little to sustain itself but its pride and little to export but outstanding design.

Aalto, to be sure, was as enthusiastic about the gospel according to Gropius and LeCorbusier as any other young architect between the two world wars. But as a Finn he could never fully embrace it. Nor did he denounce it.

He simply did what he had to do. He designed handsome furniture made of wood, which is the smart thing for the smart young to furnish their first apartments with. He used glass sparingly and brick creatively. Like Frank Lloyd Wright, he designed many of his buildings to look as though they grew out of the soil. This also made them look natural and endearing. His architecture was often exuberant and almost ornate to offset the wintery austerity of his country and to delight Finland's forest sprites.

Alvar Aalto, in sum, was an architect whose creative genius was guided most of all by the dictates of his time and place. All great architects are. To be otherwise is either pretense or fake. There is no greatness in mere originality. There can be no greatness out of context or in the wrong context.

And if people today recognize Alvar Aalto's greatness, it is because people have more generally recognized that historic continuity and context in architecture are more important than abstract stunts -- or have they?

The trouble with the well-traveled exhibit at the AIA headquarters is that it was created at the time when Aalto's friends and admirers -- and perhaps Alvar Aalto himself -- were still hellbent on proving to the world that their man was a tried and true Modern.

The exhibition emphasizes Modern row houses and apartment towers which, like all Interntional Style row house and apartment buildings, might have been designed by any old architect for Timbuktu or the Bronx. Aalto's friends and admirers would hardly feature them today.

I had much the same reaction to this exhibit as I had in December 1963, when I first reviewed it in this space. I loved the rustic quaintness of the town hall in Saynatsalo and deplored Aalto's cultural center in Wolfsburg, the city where Volkswagens are made. "It does not," I wrote, " as a cultural center in an industrial town should, contrast with the monotony and drabness of factory work. Rather, like most department stores, say, it strives to overcome the humdrum of industrialized life with brazen flashiness." s

I regretted that the exhibition omits the two buildings Aalto designed in this country -- the Finnish pavilion at the 1939 New York World's Fair and the MIT student dormitories at Cambridge, Mass., of 1948 -- but noted that sweeping curves and undulating walls, rough brick and bend wood had, even by then, lost their novelty value. They do not by themselves make Aalto the great, witty, humanistic architect he was. We have to see his work in its native context to understand and admire him. native context to understand and admire him.

The exhibit at the AIA Building (1735 New York Ave., NW) is open until Aug. 4.It was underwritten by the Graham Foundation for Advanced Studies in the Fine Arts and circulated by the Smithsonian Institution Traveling Exhibition Service. Notes From the Sidewalk

That small, playful concrete pyramid in front of the Brazilian Embassy on Massachusetts Avenue is like a cheerful twinkle on the solemn face of that awesomely and artfully cantilevered glass box. It has a function, too, that pyramidlet. It tells us the house-number -- 3006.

Then I.M.Pei came along and put pyramidlets of glass between the old National Gallery and his new East Building. Being small, they make the plaza look larger -- pyramidian Piranesi, as it were. Splashing water, they make us wet. Being of glass, they funnel light into the subterranean cafeteria.

But what is the function of that 4-foot-high brick pyramid at 1776 G. St., NW? Dogs, I am afraid, will find it too slanted. It's too rough to slide down on and too high to scrape the mud off your shoes. Is it art for art's sake?

It costs us 25 cents to go shopping in the central business district on Metro's "Downtowner" bus. It only costs 10 cents to get out again.

Wrong message. The purpose of the service is to lure shoppers downtown to help business.