Two years before the official opening of the Twin Towers in 1973, PopSci reporter Robert Gannon visited the 110-story construction site – and nearly chickened out. To reach the top of the world’s tallest building, Gannon had to climb wobbly wooden ladders lashed to metal beams (while the builders teased him for his “hippie mustache.”) “More and more open spaces in the building’s skeleton, my boggled mind noted. I looked across to New Jersey. The day was one of those rare clear ones when New York City shimmers in the crystal air.”

When he finally crawled to the edge, with mid-winter winds blowing straight through his coat, Gannon looked 100 feet down at the Empire State Building and thought the city “lay like a balsa, three-dimensional model of lower Manhattan… a plane flew around a toy Statue of Liberty stuck into a smudge of mud.”

Read on for more from “Topping Out the World’s Tallest Building.”

Gannon, wearing white hard hat, is silhouetted against completed tower. Second tower can be seen at left

Wooden ladders like this one took Gannon from the 102nd floor to the 110th. They wobbled, the nervous author reports

Gene Taylor (right) talks to Gannon at the top. Pine tree (rear right) symbolizes topping out

Worker’s fire at 104th floor lets author thaw frozen hands for note-taking. Temperature: 19 degrees. Wind: Raw.

Artist’s rendering of WTC

Read the full story in our May 1971 issue: Topping Out the World’s Tallest Building.