Executive Plaza Office Building
(The Flashcube)
An Example of Mid-Century Modern Expertise


Hellmuth, Obata, and Kaussabaum (HOK), in collaboration with local architects Keene, Simpson, & Murphy, designed the nine-story Executive Plaza Office Building in 1972 in Downtown Kansas City. Construction was completed in 1974. The design of the Flashcube epitomizes the Late-Modern architectural style and represents an ultimate expression of the Modern Movement curtain wall.  From the start, the public affectionately nicknamed it the “Flashcube,” a comment on its exaggeratedly abstract reflective glass curtainwall that encloses the cubic building mass.

The Challenge

This is not your traditional historic building. When new owners embarked on an adaptive reuse to convert the 1970s office building into apartments, it offered unique lessons about applying the Standards for Rehabilitation to mid-twentieth century materials and design.

While the building was generally in good condition, the distinctive curtain wall had numerous panels with cracked or broken glass or broken seals that allowed moisture to infiltrate the insulated glazing unit. Previous efforts to spot-replace broken glazing fell short of providing a true match to the original glass, which itself had faded over time. Even if replacement panels were made to the original specifications, they would stand out next to original glazing. The result was a patchwork of various shades of blue, green, and pink. Adding yet another type of glazing would further compromise the building’s primary character-defining feature, the uniform glass walls. The developer proposed replacing all the glass with new, matching panels.

Our Solutions

This proposal illustrates how the two components Standard #2 of the Secretary of the Interior’s Standards for Rehabilitation can be in direct conflict.

“The historic character of a property shall be retained and preserved. The removal of historic materials or alteration of features and spaces that characterize a property shall be avoided.”

– The Secretary of the Interior’s Standard for Rehabilitation #2

Rosin Preservation worked closely with the reviewing agencies to develop an interpretation that would meet Standard #2 but also adapt to the design qualities that make this late-twentieth century building significant.

Retaining and preserving the historic character of the Flashcube, specifically the uniformity of the reflective glass on all elevations, required removing and replacing all remaining original glass. The work was approved and performed as proposed. The renewed uniformity of the reflective glass curtainwall, the building’s primary character-defining feature, restored the highly abstracted appearance of the Flashcube.

In this case, restoring the entire exterior façade cladding was deemed more important than “losing” any extant historic elements.


Other Mid-Century Modern Project Experience:


720 Main Street Kansas City, MO