Day and night for more than 40 years, the tall, 4.6-meter (15 ft) red letters atop the world headquarters of Jehovah’s Witnesses have been a familiar sight to residents of New York City, many of whom depend on the sign’s useful time-and-temperature readout.

Eboni, who can see the sign from her apartment in Brooklyn, said: “It’s nice to look out the window to see the time and temperature before I go to work. It keeps me on time and helps me dress for the weather.”

Will the time-and-temperature sign be there for another 40 years? Probably not. With the planned relocation of Jehovah’s Witnesses’ world headquarters to upstate New York, that decision will rest with the future owners of the building.

A sign was originally installed more than 70 years ago by the previous owner of the building. Jehovah’s Witnesses changed it to its present form after purchasing the building in 1969.

The sign requires regular maintenance. Several generations of young men have worked on the sign, performing needed repairs at all hours.

A night worker recalls: “One evening we got a call from a television news director. He was calling to tell us that the clock on our sign was 15 seconds off. He wanted us to fix it so that he could feature it on his program that night. Soon, a sleepy technician was at work correcting the problem.”

To make it more efficient and accurate, the sign has been modified several times. In the mid-1980’s, a display of the temperature in Celsius was added to the alternating display of the time and the temperature in degrees Fahrenheit.

In 2009, the rather inefficient neon tubes illuminating the sign were replaced with red light-emitting diodes (LEDs), which are more reliable and save over $4,000 (U.S.) annually in maintenance costs. Today this sign consumes a fraction of the electricity that it once did, making it “green” as well as red.