The two buildings that house the National Gallery of Art - the West Wing, a Greek Revival structure designed by architect John Russell Pope in 1941 and the Modernist East Wing, designed by architect I.M. Pei, of Pei Cobb Freed & Partners, in 1978 - straddle Fourth Street at a point where Pennsylvania Avenue converges with the Mall. The treatment of the pedestrian plaza that ties the new, modern building to its classical counterpart is the collaboration of I.M. Pei and Dan Kiley.
Cobblestone pavers stretch from the West Wing entrance to the East Wing, incorporating Fourth Street itself, and play an important role in unifying the expanse between the two buildings. On the larger west plaza, Pei designed pyramidal skylights and a sunken fountain, illuminating the passage below and bringing design elements of the new building literally to the door of the old. To frame the space into an elongated court and extend the symmetry of the west building façade eastward, Kiley placed twin, rectangular groves of saucer magnolias on either side of the plaza. The east plaza is more open, providing a space for the daily play of shadows on the cobblestone paving. Between the East Wing and the Mall, Kiley planted a bank of cherry trees that forms a screen, offering a naturalistic, alternative treatment to the linear, axial nature of the adjoining Mall. Kiley also designed roof terrace plantings for the East Wing that included a small grove of tea crabapples.