The Yale University Art Gallery was Louis Kahn's first major commission and is considered one of his early masterpieces. Kahn designed the building while he was a critic at Yale's School of Architecture. The gallery introduced several new concepts for Kahn, including clear separation of spaces, symmetry, and a vocabulary based on triangles and circles. The modular concrete and brick building featured an innovative triangular staircase and a distinctive concrete roof structure that housed lighting and ventilation. The Art Gallery of Yale University established Kahn as an important architect and demonstrated his emerging style.