was the chigago sears tower opened in 1973 or 74?

Answer 1

Not sure about the source on the previous answer, but Wikipedia has the completion date as May 1973, as does the official Sears Tower website.

Construction commenced in August 1970 and the building reached its originally anticipated maximum height on May 3, 1973. When completed, the Sears Tower had overtaken the roof of the World Trade Center in New York City as the world's tallest building.

The structure was completed in May 1973.

Answer 2

After reading this I'd say 1974...

Upon completion in 1974 it became the tallest building in the world and held that record for 22 years before losing the title to Petronas Towers in Malaysia.

Built as the headquarters of Sears Roebuck & Company, the tower serves a wide range of office tenants and features a health club, restaurants, retail, an observation deck, and a conference center on the 99th floor.