Mitchell Hall

1993: Cadet Area (which Mitchell Hall is part of) becomes eligible for National Register listing
April 1, 2004: Cadet Area is listed as a National Historic Landmark District

The U.S. federal government established the Air Force as an independent branch of the military in 1947, and authorized the creation of the U.S. Air Force Academy in 1954. The USAFA was meant to be the main undergraduate university for the Air Force, similar to West Point in New York and the U.S. Naval Academy in Maryland. At the time that the USAFA was planned and constructed, the United States had already entered into the Cold War with the Soviet Union, and the Air Force was seen as the most important arm of the military for this conflict. As a result, the Air Force grew quickly, and many new Air Force officers were needed. The USAFA provided education to young men who would ideally become these new officers.

The U.S. Air Force Academy is located along the Rampart Range of Colorado, a scenic natural area made up of forested hills and valleys along the base of the Rocky Mountains. The Cadet Area occupies the highest ridge of the USAFA campus, and has a soaring view toward the open plains to the east of Rampart Range. Mitchell Hall, the USAFA dining hall, is part of the original master plan for the Cadet Area of the Air Force Academy, and is located off the main campus plaza, the Terazzo, along with other significant cadet buildings such as dormitories and academic buildings.

SOM was commissioned to build a dining hall that could seat all of the cadets (3,000 at that time) at once and feed them quickly, since the cadets' daily schedule is very regimented. The SOM design team, led by Gertrude Lempp Kerbis, wanted to make the dining hall’s interior column-free, and developed an advanced roof of steel trusses supported by sixteen perimeter columns to make this possible. SOM had initially wanted to have glass curtain walls on all four sides of the building to allow for maximum views of the surrounding site, and to have the food-preparation area on the floor below the dining area with small elevators to bring food up, but this would not allow the food to be served fast enough, and so they ended up designing the building so the main kitchen area was on the same floor as the dining area.

Mitchell Hall is a two-level building that is a 308-foot-by-308-foot square in plan. It has a flat roof with a twenty-one-foot cantilevered overhang on all four sides. The roof is described in more detail in the technical evaluation of this fiche. Cadets enter Mitchell Hall in formation through two fifty-six-foot-wide entrances that face the Terrazzo. Mitchell Hall only appears to be one story high from the Terrazzo, which is immediately north of the building, but its site slopes dramatically downward so that the dining hall’s southern facade is the equivalent of almost three stories below the Terrazzo entrances. The top floor contains the main dining area and kitchen serving space, as well as a mezzanine level along its northern side for higher-ranking Academy staff and guests above the kitchen service area. The bottom floor, eighteen feet below the dining level, has loading docks on the building's east facade and contains freezers, food storage, and employee workspaces. In addition, the bottom floor houses a more formal dining room for special events.

Similar to the other SOM-designed buildings in the Cadet Area, Mitchell Hall's exterior material palette consists of steel structural elements, aluminum detailing and window frames, and gray-tinted plate-glass walls on all sides except for the northern facade, which is finished with exposed-aggregate precast-concrete panels. While the structure for the upper level is steel, the lower level's structure is reinforced concrete. SOM wanted to provide as many views to the outside as possible for the dining hall, although the glass at the USAFA is mostly tinted because of the bright Colorado sun. The interior of the main dining hall space is one open room with a twenty-four-foot-high, coffered-camp ceiling with fourteen-foot-square panels. The dining area's floor is polished brown terrazzo divided by a grid of aluminum strips that continues from the Terazzo floor outside of Mitchell Hall into the building. The stairway leading to the mezzanine level of the main dining area has white marble treads and a black steel railing, and the floor of the mezannine level is white polished terrazzo.

Mitchell Hall was designed to fit the functional requirement of feeding thousands of Cadets at once while also reflecting the forward-thinking spirit that the Air Force, the military's newest branch, wanted to project to the world. The USAFA's architectural characteristics—clean forms, often raised from the ground, clad in steel, glass, and aluminum—shared similarities with the Air Force's airplanes, and set the USAFA apart from the architecture of West Point and the U.S. Naval Academy.

1956(c)–58

The Cadet Area is sited on the Rampart Range along the base of the Rocky Mountains. Before the USAFA was built, the land it occupies was undeveloped, and consisted of a series of partially forested ridges and valleys. The Cadet Area sits atop the highest ridge on the property, and required the construction of more than ten thousand linear feet of concrete-and-stone retaining walls to give the cadets a flat plaza, the Terrazzo, around which the other main university buildings (including Mitchell Hall) are sited.

Mitchell Hall's steel-truss roof, with a clear span of 266 feet square, was the first long-span steel structure to be lifted into place, all in one piece. The roof's twenty-three Warren trusses were mostly prefabricated, but still required twenty-seven welders on-site for the final installation. Each joint of the trusses was welded for added strength, and each element had to be calculated separately, leading SOM to use some of the earliest structural-analysis computer programs. The trusses range in depth from eight-and-a-half feet to more than eleven-and-a-half feet. Once the 1,150-ton roof was assembled on the ground, it took just six hours for hydraulic jacks to lift it into place atop sixteen supporting columns.

Also significant is Gertrude Lempp Kerbis's decision to have the trusses cantilever out twenty-one feet from the dining hall's exterior walls. This allows the trusses to have a cleaner structural appearance since the cantilever keeps the roof from sagging in the center, removing the requirement for extra bracing around the interior perimeter of Mitchell Hall's roof. This overhang also gives the cadets some shelter as they march in formation into the dining hall.

Mitchell Hall is socially significant as an early example of a high-profile project whose design was headed by a woman architect, Gertrude Lempp Kerbis of SOM. Kerbis studied with Mies van der Rohe at the Illinois Institute of Technology, graduating from there in 1954 with a Master's in Architecture. That same year, she was hired by SOM. On July 23, 1954, the firm won the commission for the USAFA, and Kerbis was assigned to be in charge of the design of the Academy's dining hall. Although Kerbis designed the innovative truss roof for Mitchell Hall, she was excluded from seeing the roof being lifted into place, and was not allowed to take part in presentations to the project clients. In 1967, Kerbis founded her own firm, Lempp Kerbis Associates, which remains in operation to this day, and she also has worked throughout her career to secure equal working conditions for women in the architecture field.

The U.S. Air Force Academy has historical significance as one of the three service academies for the U.S. military, along with West Point and the U.S. Naval Academy. The USAFA was constructed for the Air Force little more than a decade after the branch was officially formed, and was built in the context of the Cold War, for which the Air Force was seen as a key component to defeating the Soviet Union. The USAFA gave the Air Force a state-of-the-art training facility for future officers, and serves a crucial role in military operations to this day.