The construction of Grand Central Terminal (often called Grand Central Station) was a massive collaborative effort led by the New York Central Railroad and two primary architectural firms: Reed & Stem and Warren & Wetmore. Reed & Stem were responsible for the overall design and the innovative pedestrian ramps, while Warren & Wetmore added the ornate Beaux-Arts aesthetic and the iconic facade. The project was spearheaded by William J. Wilgus, the chief engineer of the New York Central, who came up with the revolutionary idea of "air rights"—building the terminal entirely below street level to allow for the development of Park Avenue above it. Additionally, thousands of anonymous laborers, including many Italian and Irish immigrants, performed the grueling work of excavating the bedrock. The famous celestial ceiling in the Main Concourse was designed by French artist Paul César Helleu. In 2026, the terminal remains a testament to early 20th-century American engineering, recently enhanced by the "Grand Central Madison" expansion which integrated the Long Island Rail Road into the historic complex.