Although the building takes up the entire block, the address is "1849 C Street, NW" to commemorate the founding of the Department of Interior in 1849.

Significant aspects include wide central corridors, open courtyards, movable steel office partitions, acoustically treated ceilings, a floor reserved for mechanical equipment, and fireproofing.

Melding aspects of practicality and aesthetics, the Main Interior Building became "one of the most functional and innovative government office structures in Washington" in the 1930s.

Ickes also ensured that group assembly space and employee amenities were added to the building, including the Conference Hall (Auditorium), the Activity Space (Gymnasium), the Cafeteria with courtyard, the Employees Lounge (South Penthouse, now offices) with soda fountain, the Interior Museum, the Art Gallery (currently used for offices), the Indian Arts and Crafts Shop, the Broadcasting Studio (North Penthouse), and the parking garage.

Decorative detailing such as bronze grilles and hardware, the light fixtures, and plaster moldings, "reflecting the architect's and his client's concern for design materials and craftsmanship."

[2] As in other aspects of the building design, Ickes was involved in every step of the artwork: The Secretary reviewed preliminary sketches and often provided valuable critiques.

He saw each work of art as a medium to expound upon the administration's philosophy of conservation or to portray one of the programs of the Interior Department.

[2]In Ickes' official portrait, the plans for the Main Interior Building are shown lying on the table in front of him.

Ickes wanted to promote Native American art, as the Bureau of Indian Affairs was included in the cabinet department.

The building was designed to include a shop in which arts and crafts by living Native American artists would be sold.

Today, the Indigenous Peoples Craft Shop on the first floor continues to include work by Native American artists.