These should be humbling times for the Transamerica Pyramid. This week it ceases to be our city’s tallest building. Top honors instead will go to the still-ascending Salesforce Tower.

But in architecture, size goes only so far. And when the construction dust settles, don’t be surprised if the 853-foot eccentricity that debuted in 1972 is still the tower that comes to mind when people think of San Francisco.

It’s the symbol of the global metropolis that emerged here after World War II, a corporate attention-getter that lives up to branded hype. The visual shorthand for filmmakers and postcard peddlers who want to make their (literal) point. The embodiment of San Francisco’s tension between old and new, cutting-edge and quaint, flamboyant and matter-of-fact.

None of this will change once the Salesforce Tower at First and Mission streets passes the 853-foot mark, as the building’s concrete shaft is scheduled to do Friday. The eventual height will be 1,070 feet, with a completion date of next summer.

After all, if statistics alone mattered, then the 7-mile-long San Mateo Bridge would be the structural symbol of the region — not the Golden Gate Bridge that by comparison stretches a mere 1.7 miles. For that matter, the Transamerica Pyramid as of today is only the 40th tallest building in the United States.

But just as the Golden Gate Bridge stirs emotions that have nothing to do with transportation, the Transamerica Pyramid, designed by architect William Pereira, instantly says, “You Are Here.”

Examples? It’s the one recognizable peak on the skyline of 23rd century San Francisco in 2009’s reboot of “Star Trek.” Two years later it starred on an Occupy SF leaflet calling for a Financial District protest. When holiday cards go on sale next month, it’s sure to be the centerpiece image of at least one or two.

The 48-story stiletto also remains the registered trademark of the company that built it — even though Transamerica no longer has any employees in San Francisco.

“Our logo is inseparable from the (original) building,” said Gregory Tucker, head of public affairs for Transamerica. He works at the company’s headquarters in Baltimore — a flat-topped high-rise that is crowned by that branded image of the tower out west. “I lived in Europe seven years and I can tell you, it’s one of those icons that is instantly recognizable.”

This symbolic shorthand is all the more remarkable because the Pyramid began life as a lightning rod. It attracted the fury of residents and onlookers across the country, all of them afraid that San Francisco was changing — and changing for the worse.

The design was unveiled with fanfare in January 1969, with Mayor Joseph Alioto beaming alongside Transamerica officials. The Chronicle’s front-page story the next day proclaimed the design to be so unusual “it might have drawn a wink or a gasp from the Sphinx.”

The gasps instead came from almost everyone else.

Neighbors filed lawsuits at a time when such tactics were rare. One protest featured marchers wearing dunce caps. When the Bay Guardian weekly in 1971 published “The Ultimate Highrise,” a book-length diatribe in support of a ballot initiative to place a six-story height limit on new buildings , the coverimage portrayed an ominous-looking caricature of the Pyramid under construction.

After it opened, though, most dissenters shrugged and then smiled. A favorable 1976 review in the New York Times asked, “What was all the fuss about?”

The reason that the Transamerica Pyramid has such power is that it’s an unforgettable (whether good or bad) high-rise in an unforgettable setting. The diagonal lines slide up from diagonal Columbus Avenue, which rolls toward Aquatic Park, shattering the street grid as surely as Pereira shattered downtown’s vertical maze of boxy office towers.

The Pyramid also becomes the hinge between the large-scale Financial District and the low-slung neighborhoods to the north. You get a full-frontal view from North Beach and Telegraph Hill — districts that for many regional residents and visitors remain the cultural heart of the City. Sit in a Columbus Avenue cafe sipping cappuccino, or step out the door of City Lights, and the Pyramid stands serenely above the clutter of overhead wires and sidewalk fuss.

Front and center. Nothing else comes close.

Salesforce Tower, no matter how elegant the proportions or details, will always be part of the crowd. An extrapolation of height amid other towers, clad in a paneled suit of metal and glass like all the other recent buildings around it. And it’s in a part of town that’s virgin terrain for most people, rather than a fondly remembered landscape of the past.

This doesn’t mean the tapered obelisk, designed by Pelli Clarke Pelli Architects, is “inferior” to Pereira’s once-scorned concoction. Time will render the verdict.

But the buildings that resonate with the general public do so for reasons beyond architecture. The Pyramid is the Pyramid — and no matter how many tape-measure contenders crowd the skyline south of Market Street, I’m betting that will always be the case.

John King is The San Francisco Chronicle’s urban design critic. Email: jking@sfchronicle.com Twitter: @johnkingsfchron