Late in 1928, Mies van der Rohe began to design the pavilion that would represent Germany at the 1929 Barcelona International Exposition, the first such event in which the country had participated since its defeat in World War I. The democratically elected postwar government had made its aspirations for the pavilion clear: the building was to represent "our desire to be absolutely truthful, giving voice to the spirit of a new era." The state made few other demands, leaving Mies free to pursue his most radical architectural expression of free-flowing space, bounded only by rich but abstract surfaces of Tinian marble, mirror chrome, plate glass, and onyx.
Since the pavilion was demolished when the fair was over, relatively few later audiences and architectural critics had ever seen the building except through the filter of period black-and-white photographs, and its significance became largely a matter of thirdhand debate rather than actual experience. In time it came to be interpreted in terms of Mies's later, more rational work of the 1940s and later, often derided as simple "glass boxes". This unfinished and little-published rendering of the interior, however, reveals another attitude, more sensual than objective. To the right of the column whose outlines are sketched in the center of the drawing, Mies carefully renders the view from the main space through a glass wall into the courtyard, with its reflecting pool and a sculpture of a reclining figure. Rather than making the glass look fully transparent, he gives the dark green Tinian marble different shadings behind the wall and to the left and right of it, approximating the visual effect of the screen of gray glass. Even the reflection of the sculpture in the pool is studiously considered.
from Matilda McQuaid, ed., Envisioning Architecture: Drawings from The Museum of Modern Art, New York: The Museum of Modern Art, 2002, p. 70