Johnson designed a two-story portico with five arches that faced east toward the city's skyline. The arches and their tapered support columns were clad in creamy Texas shellstone. The remaining three sides of the 20,000-square-foot building were also covered with shellstone cladding. Sheltered by the arched portico, the museum's front wall consisted of a two-story curtain of glass windows with bronze mullions. Johnson identified Florence's Loggia dei Lanzi and Munich's Felderrnhalle as precedents for the "boxes with fronts" style portico. The main entrance lead directly into a two-story hall adorned with the same type of shellstone used on the exterior, teak wall coverings, and a floor of pink and gray granite. Beyond the main hall were five small galleries of equal size for the display of art. On the mezzanine level were five similar galleries, each with a balcony that overlooked the main hall. These mezzanine galleries served as library and office spaces. To take advantage of the expanse between the two-story portico and the site's eastern boundary, Johnson designed a series of broad steps and terraces extending away from the building, with an expansive sunken, grassy plaza as the centerpiece, pointing toward the city's center.
