The diamond grid is not an ornamental facing: it holds up the building, along with a central core. “Diagrid construction” is a little more common today, but still fairly unusual; perhaps the most famous or notorious example of it is the Gherkin in London. This was a very early example. It was finished in 1964, and although it was originally built for IBM, it fits its current owner very well: its steel grid is a good demonstration of what steelworkers are capable of. The architects were the New Orleans firm of Curtis and Davis.
United Steelworkers Building (IBM Building)
United Steelworkers Building from the Boulevard of the Allies
Architects Curtis and Davis enlivened what would have been a simple square box with a distinctive diamond-grid facing that continues down into the pillars at ground level.