The Gallery's campus includes the original neoclassical West Building designed by John Russell Pope, which is linked underground to the modern East Building, designed by I. M. Pei. This new structure which was opened on May 30, 1978 is located to the east of the original building.
The design of the East Building by the architect is rigorously geometrical, dividing the trapezoidal shape of the site into two triangles: one isosceles and the other a smaller right triangle. The space defined by the isosceles triangle came to house the museum's public functions. That outlined by the right triangle became the study center. The triangles in turn became the building's organized motif, echoed and repeated in every dimension.
The building's most dramatic feature is its high atrium designed as an open interior court, it is enclosed by a sculptural space frame spanning 16,000 square feet (1,500 m2). The atrium is centered on the same axis that forms the circulation spine for the West Building and constructed in the same Tennessee marble.(Text source: Wikipedia)