The Brooklyn Bridge links two of the most populous boroughs in the United States, Manhattan and Brooklyn, which was an independent city until . With a span of almost two kilometers, the Brooklyn Bridge was the world's longest suspension bridge when it opened in .

The project took more than 13 years to build and cost more than $25 million. Engineer John Augustus Roebling came up with the design. The towers and network of steel cables in his plan have made the bridge a structural and cultural icon and an integral part of the New York . After his death, Roebling's son, Washington, took over the project.

A year after the bridge opened, circus P.T. Barnum demonstrated its safety by leading a of 21 elephants across it. Now, 125 years later, more than 126,000 vehicles make that same every day.

The bridge is also a popular subject of architectural and photographic , and is often seen in movies set in New York City.

In , it was declared a National Landmark.

Speaking at the bridge's 125th birthday celebration, New York Mayor Michael Bloomberg called it an inspiration and an unparalleled engineering .

"Since the brave began digging the foundation in the 1870s, the Brooklyn Bridge really has been the stuff of dreams, a New York City icon and enduring symbol of America's greatness. And President Chester Arthur proclaimed it the wonder of the world," he said.

A Navy punctuated Bloomberg's comments at a park concert to the festivities.

Hundreds of New Yorkers and visitors, young and old, participated in the party, listening to a range of musicians, including Brooklyn's own Philharmonic .

Other performers included Harlem-based youth IMPACT, with the song that earned them an Academy Award nomination, "Raise It Up."

Multi-award winning composer Marvin Hamlisch ended the concert with a special tribute. "So hip hip hooray, hip hip hooray, what more can we say or do? Happy Birthday Brooklyn Bridge, and many more Brooklyn Bridge, Happy Birthday Brooklyn Bridge to you!," he said.

Mayor Bloomberg and Brooklyn Borough president Marty Markowitz presented a cake in the of the bridge and led the crowd in a slightly version of "Happy Birthday."

A bridge lighting ceremony and ended the night to the oohs and ahs of the observers.

A film series, and a bike tour are among the other events scheduled to celebrate the birthday of the Brooklyn Bridge.