What may be the earliest remaining neon sign in Los Angeles—the 1927 sign that once sat atop Westlake's Hotel Californian near Mac Arthur Park—will blink back to brilliant life tomorrow.

The 40-foot-by-15-foot, red-and-blue sign will light up for the first time since it was rescued from a city storage yard near Griffith Park, where it and a companion sign had languished since the 1925-era Hotel Californian at Sixth and Bonnie Brae streets was demolished after an arson fire in 1995.

"It's one of the earliest—if not the earliest—remaining signs in Los Angeles, which in and of itself gives it a cachet that not many other things have," said neon sign restoration specialist Paul Greenstein, who painstakingly restored and renovated the sign over the course of three years.

The sign will sit atop the newly constructed Paseo at Californian on the site of the old hotel. The building comprises 53 affordable apartments for low-income families and was developed through a partnership of city and state agencies, according to Richard Schave, an LA architectural historian and founder of Esotouric, which will take part in Thursday's ribbon-cutting ceremony.

The sign almost didn't make it. Owners of the Hotel Californian constructed two neon signs in 1927, two years after the hotel opened. That was only a few years after the first neon signs appeared in the United States around 1923, Greenstein said.

The signs sat in a city storage lot near Griffith Park for nearly two decades after they were removed. One was in pretty good shape; the other was “just trashed,” Greenstein said. Rumors say actress Diane Keaton got the good one to put in her backyard; Curbed was not able to confirm that.

Greenstein was commissioned to restore the remaining one, working with Sign Image in Chatsworth on the project.

"It was cut in half. It was rusted out. It was graffitied. It was smashed. It was bent. It was on the cusp of not retrievable," he recalled.

Ultimately, Greenstein determined he could salvage the sign. He cut the sign's letters off the old twisted frame, which had been cut into pieces to be removed from the old building. He straightened them out and reworked them, adding new metal where necessary.

"When I stripped it, there's always bits of original paint left over. ... And I could see the interior was cream-colored, and the exterior was ... orange. Like a Creamsicle," Greenstein said. "And the letters 'Hotel' are neon red. And the word 'Californian' is mercury argon blue."

Finally, he and his crew reinstalled the sign on a new frame the builders of the Paseo constructed on the roof. Greenstein only began relighting the sign this week. It will light up completely for the first time in decades on Thursday.

Schave said the sign's restoration is important for Los Angeles. "Neon signs are really important," he told Curbed. "Electrographic architecture, as Tom Wolfe called it. And it is one of the most iconic aspects of Los Angeles design and its silhouette and landscape ... So this is really important. It's one of the earliest, and it should be celebrated."

For Greenstein, the sign's revival is personal. "I'm proud of it," he said. "When it's running, it's going to be a pretty impressive thing. You're going to be able to see this thing from any of the office towers downtown. ... So that it gives it a kick in the ass. And then just the fact that someone's putting some money into something in the MacArthur Park area is a kick in the ass."

Greenstein will speak at Thursday's ceremony, as will civic leaders responsible for the Paseo. The ceremony begins at 10:30 a.m. at 1907 West 6th Street.