On June 8, 1901, photographers captured workers tearing up the earth around New York City’s Union Square. This massive, chaotic engineering project was part of the construction of the city’s historic first subterranean rapid transit system—the Interborough Rapid Transit (IRT)—which would fundamentally reshape Manhattan’s geography when it finally opened three years later.
Building this specific section required an immense feat of structural acrobatics. Engineers had to carefully excavate massive tunnels directly underneath operating streetcar lines, maze-like networks of gas mains, and heavy building foundations without causing the bustling city above to collapse. They accomplished the entire project using manual labor, horse-drawn carts, and sheer mechanical ingenuity.
