It’s a sure sign of the season in Birmingham, Alabama.

Every year – on the first night after Thanksgiving – the massive Christmas trees, the festive wreath, and the huge stocking take their place, illuminating the windows of Birmingham’s 30-story Regions Center, headquarters of Regions Bank.

It can be seen for miles. Driving north along Interstate 65 at night, it’s often the first thing you notice once you pass through Red Mountain. Landing at the Birmingham-Shuttlesworth International Airport, folks flying in get a bird’s-eye view showing the west and north sides.

The Regions Center Christmas display brightens the holidays for folks in Birmingham. (Regions Bank)

Here’s the inside view of how it all comes together.

It usually starts a few months before Christmas. Crews begin combing through the offices of the Regions Center, using grids showing them which colors go on which windows to form the designs.

And while a lot of people think there’s a computer system that control it all, it’s actually a very manual process.

Before the Regions Center was completed in 1971 (when the building was shared by the First National Bank of Birmingham and a company called Sonat – or Southern Natural Gas), a light tube was placed above every window starting on the fifth floor. The idea was to have the building displaying bright light every evening.

The energy crisis of the 1970s curtailed those plans. But the story goes that in the following years, a Sonat executive saw a building in Houston that had a similar “curtain wall” design and used it to illuminate a Christmas display during the holidays. He brought the idea back to Birmingham, and Regions Bank has proudly continued the display each year.

To create the Christmas tree, wreath and stocking designs, “gel sleeves” are slid over the light tubes in every window that’s part of the display. Testing happens late at night or early in the morning in the weeks leading up to Thanksgiving to ensure each window on every floor is ready to glow with the right color when the Christmas season begins.

Putting together the annual display at Regions Center is a highly manual process. (Regions Bank)

Those working in the building are accustomed to the lights popping on automatically around 4:45 p.m. each afternoon. They turn their window blinds in a way that helps the light reflect as brightly as possible to enhance the display.

Why do crews have to manually set up the display each year? Because not too long after the holidays, crews will begin following the same process to set up a golfer image that Regions Bank displays in the weeks leading up to the Regions Tradition golf tournament each spring.

The building has been used for a few other designs over the years. In 1996, people saw the familiar Olympic torch and rings when Birmingham hosted soccer matches as part of the 1996 Atlanta games. In 1991, an American flag and the letters “USA” were displayed during the Gulf War.

Over the years, the Regions Center has lit up to commemorate other events in the city and world. (Regions Bank)

“For every display, there’s a lot of work to get it just right. But we’re proud to do it,” a spokesman for Regions said. “Because it’s a tradition around here – one we’re honored to carry forward.”

A version of this story originally appeared on Regions Bank’s Doing More Today website.