Tower on top of tower On December 1, 1961, a 12-foot-high cross weighing more than 600 pounds was hoisted to the 53rd floor of the east tower – as high as it went at the time. Illuminated in red and facing south, the double-bar cross promoted Christmas Seals for the Tuberculosis Institute of Chicago and Cook County. It is now the symbol (left) of the American Lung Association.

Early in January of the next year, the idea of a beacon and “range lights,” a pair of lights used for navigation, was being discussed for Marina City. John Magill, a columnist for the Chicago Daily Tribune, proposed it. Mayor Richard J. Daley responded to this by saying it was a “good idea.”

Then in October 1962, Chicago’s first commercial television station, WBKB (now WLS-TV), announced it would erect a 426-foot tower (285-foot mast supporting a 140-foot-six-inch antenna) on the west tower. 969 feet above ground, the top of the tower would be the highest point in Chicago. It was a rental agreement worth $1 million to Marina City, equivalent to $7.5 million in 2011.

The tower, built in 1964, featured a column of red lights that flowed upward when temperatures were forecast to increase, and downward when they were expected to drop. Slowly blinking lights meant a storm was approaching. Steady illumination meant no change.

Two rings of light at the base of the tower signalled victory (white) or defeat (blue) for a Chicago sports team. A third ring represented the WBKB “Circle 7” logo.

The beacon was designed, built and maintained by White Way Electric Sign & Maintenance Company of Waukegan, Illinois (now in Mount Prospect). It was controlled from WBKB studios at Marina City.

WBKB started broadcasting from Marina City in September 1964. In 1974, WLS moved its television transmitter from Marina City to Sears Tower. Mayor Daley threw a ceremonial switch and the station went off the air momentarily, then came back with a poor signal from Sears Tower said to be almost unwatchable.

According to Mike Wilson, an engineer for KTLA-TV in Los Angeles, who worked at WLS while attending college in Chicago at the time, there had been an error in the construction of the new transmitter or antenna at Sears Tower. The station switched back to the Marina City antenna until the problem was corrected.