[4]: 212 Brown discussed the goals of the institution and its new building with the trustees and summarized them in a four-page "Policy Statement" and a nineteen-page "Pre-Architectural Program" in June 1966.

[5]: 353, 360 Brown also expanded the Kimbell collection by acquiring several works of significant quality by artists like Duccio, El Greco, Rubens, and Rembrandt.

Richard Brettell, director of the Dallas Museum of Art, said, "He was, in some ways, single-handedly responsible for turning the Kimbell from an institution with a great building into one whose collection matched its architecture in quality".

[9] In 1966, before the museum even had a building, founding director Brown included this directive in his Policy Statement: "The goal shall be definitive excellence, not size of collection."

[6] It also includes works by Duccio, Fra Angelico, Mantegna, El Greco, Carracci, Caravaggio, Rubens, Guercino, La Tour, Poussin, Velázquez, Rembrandt, Boucher, Gainsborough, Vigée-Lebrun, Friedrich (the first painting by the artist acquired by a public collection outside of Europe),[11] Cézanne, Monet, Caillebotte, Matisse, Bonnard,[12] Mondrian, Braque, Miró and Picasso.

The Asian collection comprises sculptures, paintings, bronzes, ceramics, and works of decorative art from China, Korea, Japan, India, Nepal, Tibet, Cambodia, and Thailand.

Precolumbian art is represented by Maya works in ceramic, stone, shell, and jade, Olmec, Zapotec, and Aztec sculpture, as well as pieces from the Conte and Huari cultures.

The African collection consists primarily of bronze, wood, and terracotta sculpture from West and Central Africa, including examples from Nigeria, Angola, and the Democratic Republic of the Congo, and Oceanic art is represented by a Maori figure.

[10] The museum also houses a substantial library with over 59,000 books, periodicals and auction catalogs that are available as a resource to art historians and to faculty and graduate students from surrounding universities.

[4]: 210 After an extensive search that included interviews with such noted architects as Marcel Breuer, Mies van der Rohe, Pier Luigi Nervi, Gordon Bunshaft and Edward Larrabee Barnes, the commission was awarded to Louis Kahn in October 1966.

[16] Approaching the main entrance past a lawn edged by pools with running water, the visitor enters a courtyard through a grove of Yaupon Holly trees.

The sound of footsteps on the gravel walkway echoes from the walls on either side of the courtyard and is magnified under the curved ceiling of the entry porch.

[5]: 354  Harriet Pattison played the lead role in the landscape design and is also the person who suggested that open porches flanking the entrance would create a good transition from the lawn and courtyard to the galleries inside.

Further research by Marshall Meyers, Kahn's project architect for the Kimbell museum, revealed that using a cycloid curve for the gallery vaults would reduce the ceiling height and provide other benefits as well.

The relatively flat cycloid curve would produce elegant galleries that were wide in proportion to their height, allowing the ceiling to be lowered to 20 feet (6 m).

Kahn generally referred to the museum's roof form as a vault, but Komendant explained that it was actually a shell playing the role of a beam.

Not fully understanding the capabilities of modern concrete shells, Kahn initially planned to include many more support columns than were necessary for the gallery roofs.

[14]: 194 The Geren firm, which had been asked to look for ways to keep costs low, objected that the cycloid vaults would be too expensive and urged a flat roof instead.

Kahn, however, insisted on a vaulted roof, which would enable him to create galleries with a comforting, room-like atmosphere yet with minimal need for columns or other internal structures that would reduce the museum's flexibility.

Virgil Earp and L. G. Shaw, Byrne's project superintendents, designed forms with a cycloid shape that were made from hinged plywood and lined with an oily coating so they could be reused to pour concrete for multiple sections of the vaults, helping to ensure consistency.

[14]: 204–206  The long, straight channels at the bottoms of the shells were cast first so they could be used as platforms to support the workmen pouring concrete for the cycloid curves.

After all the concrete had been poured and strengthened with internal post-tensioning cables, however, the curved parts of the shells carried the weight of their lower straight edges instead of the other way around.

"[15]: 132  Robert McCarter, author of Louis I. Kahn, says the entry gallery is "one of the most beautiful spaces ever built", with its "astonishing, ethereal, silver-colored light.

"[5]: 355  Carter Wiseman, author of Louis I. Kahn: Beyond Time and Style, said that "the light in the Kimbell gallery assumed an almost ethereal quality, and has been the distinguishing factor in its fame ever since.

[4]: 221 [14]: 209 In areas without art, such as the lobby, cafeteria and library, the entire reflector is perforated, making it possible for people standing beneath to glimpse passing clouds.

[4]: 221  The result is that the strong Texas sun enters a narrow slot at the top of each vault and is evenly reflected from a curved screen across the entire arc of the polished concrete ceiling, ensuring a beautiful distribution of natural light that had never before been achieved.

[citation needed] In 1989, director Ted Pillsbury, Brown's successor, announced plans to add two wings to the north and south ends of the building and chose architect Romaldo Giurgola to design them.

In 2006, the idea of an expansion surfaced once again at a dinner in Fort Worth attended by Timothy Potts, the museum's director at the time (Eric M. Lee has been the director since March 2009); Kay Fortson, president of the Kimbell Art Foundation and a key figure in the creation of the original building; Ben Fortson, a trustee; and Sue Ann Kahn, Louis Kahn's daughter and a vocal opponent of the original plan for expansion.

Piano was an obvious choice because he had worked in Louis Kahn's office as a young man and had later established a reputation as one of the world's leading museum architects.