Southern California's early shopping centers helped define the vast spaces surrounding them. Classic centers in Lakewood, West Covina, Westchester and other cities have been altered, replaced or sent to some giant recycling center in the sky. But Norwalk, in the belly of the Los Angeles basin, has managed to keep its vintage shopping center pretty much as it was when it opened 47 years ago. Although a recent face-lift has given the stores a "Spanish" flavor, the center's 110-foot sign remains virtually untouched. It was erected at Pioneer Boulevard and Rosecrans Avenue in 1954 on a relentlessly flat suburban plain perfect for a tower visible a mile away by day and five miles by night. The steel girder framework, designed by the architectural firm of Stiles Clements, was an appropriate icon for atomic-age exuberance. Like a rocket gantry, cables anchor a shaft topped by a grid that displays the center's name to the east, west, north and south with compass-like precision. (The arches were added later.) Dubbed a "Beacon to Better Buys" when the center opened, the city's premier landmark still blazes away, drawing shoppers to its commercial flame.