The “diagrid” construction of the United Steelworkers Building (originally the IBM Building) is unusual, both from an aesthetic and from an engineering standpoint. The grid is not just decorative: it holds up the building from the outside. The piers on which all that weight rests are dramatic from close up. The architects were Curtis and Davis of New Orleans; as far as old Pa Pitt knows, this is their only building in Pittsburgh.

More pictures of the United Steelworkers Building from Gateway Center Park, from the Boulevard of the Allies, and from across the river.