Mysterious puzzle on California building finally solved

At first glance, it looked like a decorative art installation. Look closer (much, much closer), and you may have realized the spinning circles at the top of Adobe’s headquarters in downtown San Jose were a puzzle waiting to be solved.

After three years of playing on repeat, the code has been finally cracked. Software engineer Brian Vincent solved the semaphore this spring, Adobe announced, staring at and analyzing the circles’ rotations until he ultimately realized it was conveying an image from the “Birth of Venus” painting by Italian Renaissance painter Sandro Botticelli.

A semaphore is a way to send a visual message. It can be done with waving flags, fire or flashing lights. Think of Paul Revere’s famous example, when he used lanterns to signal the British were coming.

In the case of the San Jose Semaphore, there are four circles that can each appear in four positions, making a total of 256 possible combinations between them. The puzzle first debuted in 2006, transmitting a message on a loop. The circles take a new position every 7.2 seconds.

This version of the puzzle has been playing repeatedly since May of 2023, waiting for someone to figure out its message.

“I wanted to create a code that was impossible for me to solve,” said its creator and artist Ben Rubin.

The first-ever San Jose Semaphore from 20 years ago broadcast the full text of the novel “The Crying of Lot 49” by Thomas Pynchon. The second was broadcasting an audio file instead: the the famous Neil Armstrong quote “One small step for man, one giant leap for mankind.”

This puzzle, the third in the semaphore’s history, was transmitting a visual medium: a small segment of a Renaissance painting.

How is that possible? Well, it turns out it’s extremely complicated. It took years for someone to solve it, after all.

In the simplest terms, the circles were essentially transmitting a code for colors in the pixels of a digital image. Vincent spent years agonizing over the four circles’ rotations until he finally discovered the solution. It was a code for one small rose from the “Birth of Venus.” (Hear more about how Rubin crafted the tricky puzzle and how Vincent cracked the code in the video at the top of this story.)

“I want to say that the difficulty level on this puzzle is probably perfect,” Vincent said. “In some ways it seems a little bit simple, but at the same time it takes a lot of work and a lot of effort, and it stands for years before anyone solves it.”

Now that the code has been cracked, it’s time for a new puzzle. A fourth semaphore is planned for the San Jose building, Adobe said. Whoever solves the next one will get a two-year subscription to Adobe Creative Cloud and major bragging rights.