The top of the building is oriented toward the lakefront, and is often said to resemble a sailboat.

The building was originally planned to be 5 stories taller.

Located at the northwest corner of Grant Park, on the former site of the John Crerar Library.

The southeast section is cut away at the base, except for a triangular column containing a public stairway to the nearby Metra train station.

The diamond-shaped slope is outlined with white light bulbs. Around holidays they used to be replaced with colored lights.

The official count of 41 floors does not include 5 levels of unused space in the narrowest portion at the top of the diamond.

The building appears to be split diagonally down the middle. The right and left sides are slightly disjointed, and at the top they are actually separated by a gap.

The building's designer was Sheldon Schlegman of A. Epstein & Sons.

Originally planned as One Parke Place, this was billed as the world's first computerized office building.

The service cores are rotated 45° from the street grid, producing diagonally-oriented office floorplans which take advantage of the extraordinary southeast views.

On special occasions the windows inside the diamond are lit in patterns spelling short messages or sports team names.

A sculpture by Yaakov Agam used to occupy the triangular niche at street level. Called "Communication - X9", its colorful geometric patterns would change when the viewer walked past.

This building was featured prominately in the 1987 motion picture "Adventures in Babysitting" starring Elisabeth Shue.