New York Subway groundbreaking

On May 17, 1904, construction officially began on the Interborough Rapid Transit Company's subway system beneath City Hall in Manhattan. Chief engineer William Barclay Parsons oversaw the ambitious project that would connect lower Manhattan to Harlem. The line opened later that year with electric multiple-unit trains, revolutionizing urban mobility. It alleviated street congestion and set standards for subway design worldwide, including deep-level tunneling techniques still used today.