Finished in 1883, the Brooklyn Bridge was one of the first in the world to use steel suspension cables to hold up the roadway. The cables themselves, almost 16 inches in diameter, are woven from 5,434 individual wires. The result was a far more sturdy bridge than the iron structures being built at the time.

The bridge also paved the way for uniting Brooklyn with the rest of New York -- creating what would eventually become (and remain for decades) the largest city in the world.

Its construction was not without tragedy. At least two dozen men lost their lives, including the bridge's chief builder John Roebling, who died as a result of an infection from a crushed foot.

After his death, his son Washington took on the role of chief engineer, but Washington himself suffered a debilitating case of the bends while working under the East River. Afterward, he used a spyglass to supervise construction from a bedroom overlooking the project in Brooklyn Heights. His wife Emily would convey orders to the construction crew, becoming what's believed to be the first female field engineer.