The Atelier 505 mixed-use development contains theaters and arts facilities to expand the Boston Center for the Arts, commercial and retail spaces, and over 100 residences. The new building treats the entire city block as a conceptual unit divided into many buildings orchestrated relative to one another with the BCA's Cyclorama dome as the architectural centerpiece. The new building mass steps back from the face of the Cyclorama along Tremont Street, exposing the building's copper dome to the street. This stepping back also creates a triangular public plaza, animated by landscaping, paving patterns, café seating, shopfronts, display windows, and lobby entrances. This plaza is a simple stage-like surface for activities that spill from the building. The architecture reinforces this activity by its mix of program and by its activation of the street, with multiple entrances to retail, housing, and public functions. The new construction is designed to read as several volumes, rather than as a single monolithic building, in order to allow for transitions in scale and to echo the nature of the South End fabric.