The 60-by-60-foot (18 m × 18 m) clock face, with a 35-foot (11 m) minute hand and a 25-foot (7.6 m) hour hand, both of laminated aluminum, is nearly twice the size of London's Big Ben, and was built in Georgia by Audichron for $12,500 and shipped to Pittsburgh. The clock, designed by Audichron founder John L. Franklin, is driven by a 1.25-horsepower (0.93 kW) Janett motor.
Originally located on a Mount Washington hillside, the clock's face was used as advertising for a succession of beverages, including Coca-Cola, and Fort Pitt, Ballantine, Carling, and Schlitz beers. In 1961, the Duquesne Brewing Company bought the clock, painted its "Have A Duke" slogan on the face and installed it atop its building in the South Side where it has been running since.
After the brewery closed in 1972, the clock was leased to Stroh's Beer, then WTAE-TV Channel 4. After WTAE's lease ended in 1993, the clock continued to run without an ad. The Pittsburgh Brewing Company paid $44,000 to repair the clock when it took over in 1999, paying $5,000 a month to show its logo on the face. In 2002, Equitable Gas paid to have their name placed on the clock. In October 2009, AT&T took over the rights to advertise on the clock and has redesigned the face to display the traditional blue and white AT&T logo.
According to wikipedia