Constructed as the first real underground parking structure in Dallas, the garage was accessed from Jackson, Prather and Harwood Streets and was capable of holding 1,250 cars in a continuous spiral.

Broad & Nelson designed an 8-floor, 201,297 sq ft (18,701.1 m2) addition on top of the existing structure, and the building was connected by an underground pedestrian tunnel to the growing Mercantile complex.

[4] The Continental Building's office space became vacant when Mercantile National Bank moved to new headquarters at Momentum Place in 1987, but the garage continued to be used.

Thornton, one-time president of Mercantile National Bank (and later Mayor of Dallas) commissioned a 30-foot (9.1 m)-high mosaic sculpture for the building by acclaimed California artist Millard Sheets.

The sculpture includes a cowboy, Native Americans, horses and wild animals made of carved stone and brightly colored Italian glass mosaic tiles and 22-karat gold ornamentation.