I recently found that New York City has the world's largest clock, the Colgate Clock: the dial is 15 meters or 50 feet, octagonal in shape.
Located on the former site of Colgate-Palmolive & Company, it is a reminder of the time when factories dominated the Jersey City's waterfront. The clock's design was inspired by the shape of a bar of Octagon Soap, first manufactured by Colgate as a laundry cleanser. The surface of the clock is 1,963.5 square feet and 50 feet in diameter. The minute hand is 25 feet, 10 inches long; the hour hand is 20 feet long. The timepiece can be adjusted and is maintained to stay within one minute of accurate time. There was a small master clock at Colgate that was checked against the US Naval Observatory in Washington, DC. The clock's mechanism is like that of a traditional wall clock with weights and wheels but is powered by twenty-eight large-volt batteries that are recharged.
After almost thirty-one years of enduring the elements, the clock was stopped at 9:30 a.m. on June 13, 1955, for repairs. A New York Times article reports that ". . . the laminated wooden hands, waterlogged on wet or humid days . . . , had Colgate mechanics bowlegged changing counterweights to keep the time just right. . . . Another fault had developed, too. The steel trusses that support the hands had rusted. The new clock hands will have an aluminum core with porcelained steel facing. They and the quarter-hour points will have fluorescent lighting when the clock get going again, instead of the old incandescents" (Meyer Berger, "About New York." New York Times 11 July 1955).
The replacement of the clock's hands took longer than expected, prompting hundreds of calls to the company by those counting on the clock to keep them on schedule. The installation finally took place on July 28 and July 29, and the dependable timepiece was operating again in a week ("New Hands on Big Clock." New York Times 30 July 1955). The dimensions to the hands were altered by counterbalances making for inconsistencies in published measurements of the timepiece.
Today's landmark clock replaces an earlier and smaller clock designed by Colgate engineer Warren Day and built by the Seth Thomas Company for the centennial of the founding of Colgate in 1906. The clock, 38 feet in diameter, was made of structural steel and its face of stainless steel slats. It was part of an assembly, installed in 1908, that was set upon the roof of an eight-story warehouse at the southeast corner of York and Hudson Streets, which was also built for the company's anniversary. Engineer William P. Field designed the 200-foot-long and 40-foot-high sign for both the clock and advertisement "COLGATE'S SOAPS-PERFUMES" in 20-foot-high letters. It was illuminated at night by 1,607 bulbs emitting 28,000 watts of light. From the Jersey City waterfront, it was visible some twenty miles away to Staten Island and the Bronx. It received acclaim as an identifying symbol of the company as well as for its practicality. When replaced by the present-day clock, it was retired to Jeffersonville, Indiana.
Just thought I'd pass that on...