Lord of the Rings fans rejoiced Wednesday night to see their wish come true: the Salesforce Tower’s crown was lit-up to reflect the giant fiery Eye of Sauron, the fantasy antagonist from J.R.R. Tolkien’s novels.

A Change.org petition with more than 11,000 signatures urged Salesforce to feature the evil eye on Halloween night.

As children and families went door to door for candy to fill their pillow cases and plastic pumpkin buckets, San Francisco workers and residents craned their necks up to the towering building and watched as the ominous eye with a purple hue was engulfed in rippling flames on the LED installation.

The petition, titled “Turn Salesforce Tower into Eye of Sauron on Halloween night,” wrote “San Francisco = Mordor. Salesforce Tower = Eye of Sauron. Run, you fools!” in its pitch online.

Boston Properties and Hines, the developers and owners of the tower and LED installation, granted fantasy aficionados what they requested and put the crown’s 11,000 LED lights to work more than 1,000 feet above Mission Street.

Journalists and people strolling past Salesforce Tower took to social media to share their photos and videos online as the Eye of Sauron peered across the city.

The LED installation is called “Day for Night” and was designed by electronic artist Jim Campbell. The installation was produced as part of San Francisco’s “1 percent for art” development tax.

Salesforce CEO Marc Benioff had told Curbed SF that he preferred to see the tower lit up with a symbol calling for Batkid’s return to the city because “our city needs a lot of love right now.”

Lauren Hernandez is a San Francisco Chronicle staff writer. Email: lauren.hernandez@sfchronicle.com Twitter: @LaurenPorFavor