City Hall in Colleyville, Texas, looks out on a 140-by-140-foot flat area of lawn with no trees or distinguishing features. But not for long.

City leaders envisioned turning that unadorned lawn into a dynamic public space with a critical linkage to City Hall and the Public Library . The goals included creating a signature gathering place for residents of this city of 25,000 residents nestled between Fort Worth and Dallas, while making...