Francis A. Gregory Neighborhood Library in Washington, D.C., by Adjaye Associates, 2012.

Less than a week after seeing David Adjaye give a keynote talk at Architectural Record's 2012 Innovation Conference, I found myself in Washington, D.C., the location of his competition-winning National Museum of African American History and Culture now under construction and a couple recently completed libraries he's designed. One of the latter—the Francis A. Gregory Neighborhood Library (done with Wiencek + Associates) in Fort Davis Park—was a highlight of his talk, making it a must see on my day trip to the District of Columbia.

The library is literally on the edge of the park, such that three of four sides face the trees and grass, and the fourth side faces the street. Adjaye has treated all four sides with a diamond pattern that stretches vertically as it rises from the ground to the top of the glass wall and the roof floating above. The diamond pattern is treated like a checkerboard, so the panels alternate between clear and solid. On three elevations a portal is inserted for access to the interior; two of them are flush and are used for emergency exits, while the fourth one—facing the street—projects from the glass wall as the entrance vestibule.

One step inside and the checkerboard pattern seen from outside is even richer. The pattern is not the result of different types of glasses, but instead is the result of deep wall sections articulated in wood. The double-height section to the right of the entrance is the heart of the building, the point from where most of its spaces are visible. The long and tall space is diagonally cut by the stair to the second floor, the location of the children's section, the bathrooms, and some meeting rooms. The biggest difference between upstairs and downstairs is that the borders of the spaces upstairs are held back from the wood exterior walls, creating a void and opportunities for window seats and an additional double-height space.

The interior spaces sit below a glazed roof that is articulated with a diagonal structure even more regular than the exterior walls; a lower grid over the double-height space layers more diagonals. The diagonal grid and its realization in wood and steel filters the sunlight entering the library and inversely the views looking outside. These views into Fort Davis Park are the key to Adjaye's design, something that the architect embraces but responds to through patterning rather than strictly all-glass walls. The views through diagonal apertures raise our awareness of the scene beyond and make the interior a warm and welcoming place to be.