Update, April 2020: The pyramid’s beacon, usually a rare sight, will be a constant addition to the SF skyline in the weeks to come, as building management has opted to keep it glowing nightly as a tribute to SF healthcare workers who are working to quell the COVID-19 outbreak.

According to Elaine Chan, general manager for JLL, the beacon will come on at around 8 p.m. every night. In addition to hailing healthcare providers, the light is intended to be an extra comfort to people across the Bay Area (it’s visible to several counties in the North Bay and East Bay, provided the fog gives an unobstructed view) as they continue to shelter in place, recalling imagery of a lighthouse.

Those who keep a sharp eye on the San Francisco skyline noticed a shining white light atop the Transamerica Pyramid Monday night, a spectacle that appears every so often but doesn’t cleave to any particular schedule.

That was the towering concrete high-rise’s beacon, housed within a glass-encased atrium at the top of the pyramid’s spire. While the light has shined over the city for decades, it is only switched on a few times per year, an illuminating appearance that surprises even longtime residents.

(Note: This shouldn’t be confused with the smaller, 1,000-watt red light at the very tip of the spire, which is a federally-required warning light for airplanes.)

The building’s fact sheet refers to the 32-pane glass encasement at the top as the “crown jewel,” a term credited to Transamerica Pyramid architect William Pereira. The light inside shines at a spectacular 6,000 watts, about a 100 times more powerful than a standard incandescent bulb.

The beacon is the highest point in the once-tallest building in San Francisco and has never been open to the public. Building management decides when to turn it on. According to a building spokesperson, the bright light turns on for certain federal holidays, special occasions, “or when the 49ers win championship games.”

Recently it’s been visible on Christmas, New Year’s Eve, Labor Day, July 4, and September 11. Sometimes for several days. Sometimes just one.

Monday’s luminescence was in honor of the Martin Luther King Jr. Day. In the past, it’s glowed for more obscure occasions like Firefighter Appreciation Week.

But unlike City Hall, which has a public lighting calendar, the Transamerica Pyramid doesn’t commit to a schedule. “There’s nothing to say we will absolutely light it at any time,” a building representative said in 2010.

Since only a small number of people have been to the zenith of the building, it remains a largely mysterious redoubt, although photographer Ryan Fitzsimons captured the structure in remarkable detail in 2019.

The 2018 semi-superhero film Venom is possibly the only movie to attempt to portray the very top of the building. Although visual effects artists doubtless did their best, the shot in the final film really doesn’t resemble the actual beacon, although they did at least remember to put the airplane light up there.