Ever since its grand opening in 1904, New York City's subway has remained the largest subway system in the world, with more than 700 miles of track and a billion passengers per year. This feat of modern engineering started as the brainchild of Alfred Beach, who built an experimental subway in 1868 to respond to New York's growing population and incredibly crowded streets. Local politicians who had a monetary interest in the current transportation system halted his progress and the tunnel was closed. The city continued overcrowding the streets until 1888, when a major blizzard shut down the city and Mayor Hewitt proposed building the system that transformed New York forever. Backed by a financier and an engineer, work began on the subway. This program chronicles the challenges faced by the engineer who designed the subway between a maze of buildings and through a river; by the miners and immigrants who risked their lives to build the tracks and tunnels; and by the city's residents, who endured years of blasting and construction.

Friday, 9/5/08 from 4:30-5:30 a.m. ET