4. Brooklyn Bridge
Image Source: Jason Eppink
Incredibly, this project was completed way back in 1883. At the time of its completion it was the longest suspension bridge in the world at 3,460 feet in length. It was also the first bridge project that made use of explosives and an underwater suspension system called a Caisson. The project was complicated by the fact that the chief engineer died before it was even started and had to be taken over by his son. Today the Brooklyn Bridge carries about 144,000 vehicles every day and is the second-busiest bridge in New York City.
