The workers came in extra early on their own time Saturday morning to see if they could catch the thieves in the act. At about 5:45 a.m., they spotted two men in a white van knocking over one of the streetlights.
Police responded and a chase ensued.
The suspects raced south on the 110 Freeway before crashing into a garage in Highland Park.
The men then jumped out of the van and took off running. Officers caught up with them hiding in the backyards of two homes.
"The light poles are solid brass. They're from about when Pasadena was established. They're fairly old. They weigh 700 pounds, so they're able to cut them up and sell them down in Long Beach and a few other areas in Southern California," explained Pasadena Police Department Lt. Chris Russ.
Replacement aluminum replicas cost the city about $3,000 apiece, and the valuable brass from the historic posts is worth just a fraction of that.
The arrested suspects were identified as 44-year-old Frank Bose of Lancaster and 52-year-old Steven Dickinson of Los Angeles.
Police believe the same suspects may be responsible for numerous similar grand thefts of city property.
City News Service contributed to this report.