The Sydney Harbour Bridge in Sydney, Australia, is one of the most famous structures of its kind. Tourists flock to it like selfie-taking moths to a flame, and suit up to climb over it day in and day out.

But did you know it has a twin in Bayonne, New Jersey, that most people don't even think twice about?

Bayonne is located at the end of the peninsula where you will find Hoboken and Jersey City. It's just south of both of those. The Bayonne Bridge links the city of its name with Staten Island, New York. It's almost identical to the Sydney Harbour Bridge, except that the Sydney bridge has concrete pylons on either side and the Bayonne Bridge doesn't.

The Sydney Harbour Bridge during a fireworks show. Don't hold your breath for a similar showing in Bayonne. Getty Images

It turns out the Sydney Harbour Bridge and the Bayonne Bridge are considered "sister bridges," and officials from Sydney and Bayonne attended each other's ribbon-cutting ceremonies for the identical bridges back in the 1930s.

Well, they're considered sister bridges by the Port Authority of New York and New Jersey and Staten Island news site SILive, at least. For some reason, no Sydney-centric websites appear to be playing up the similarities.

SydneyHarbourBridge.info doesn't seem to know about Bayonne, for example. And the Sydney Harbour Bridge look-alikes page on the Sydney for Everyone website fails to mention the aesthetic similarities between the two bridges.

The Bayonne Bridge, as viewed from Staten Island. Flickr Creative Commons/vaticanus

The Bayonne bridge opened to traffic first, on November 15, 1931, but construction on the Sydney Harbour Bridge began first, according to Wikipedia. The Bayonne Bridge carries four lanes of Route 440 from Bayonne to Staten Island.

It's a steel-arch bridge whose total length is 5,780 feet, Wikipedia says. Its width is 85 feet. It's longer than the Sydney bridge, but shorter, with 325 feet from the arch to the water.

The Sydney Harbour Bridge is actually shorter in length at 3,770 feet, according to Wikipedia, but wider at 161 feet across. It's 440 feet tall, so although it's shorter than the Bayonne Bridge, it reaches about 115 feet higher.

The Bayonne Bridge crosses a body of water known as the Kill Van Kull. The Sydney Harbour Bridge crosses a body of water called Port Jackson.

The Bayonne Bridge's surroundings look desolate compared to those in Sydney. Flickr Creative Commons/Raymond Bucko

The Sydney Harbour Bridge was designed by an English firm called Dorman Long and Co of Middlesbrough, according to an Australian government website. Construction began in 1924 and took 1,400 men eight years to build, using 53,000 tons of steel. The bridge carries eight traffic lanes and two rail lines. It was open to the public on March 19, 1932.

Construction started later on the Bayonne Bridge, commencing in September 1928, according to the Port Authority's website. But it was completed and open to the public first, in November 1931. The Bayonne Bridge was the product of collaboration between designer Othmar H. Ammann and architect Cass Gilbert.

The Bayonne Bridge held the record as the world's longest steel-arch bridge until 1977, when the New River Gorge Bridge in West Virginia topped it at 1,700 feet long. But according to one Australian news source, many Australian children are taught that the Sydney Harbour Bridge is the longest of its kind in the world.

The Sydney Harbour Bridge is located near the iconic opera house. Getty Images

The Sydney Harbour Bridge was opened on March 19, 1932, according to Wikipedia. Officials from Sydney and Bayonne attended each other's bridge-opening ceremonies.

The Bayonne bridge-opening and ribbon-cutting ceremony went forward without incident, but Australia's ribbon cutting didn't go as well. The ceremony and show of cultural friendship was upstaged in Australia by a monarchist.

North South Wales Premier Jack Lang was interrupted from cutting the ribbon by Captain Francis de Groot, a pro-monarchist who was offended that the bridge wasn't being opened by a member of the British Royal Family, according to Australian Geographic. He slashed the ribbon open with his sword.

If you zoom in far enough on your camera from Battery Park in New York City, you can see the Statue of Liberty with the Bayonne Bridge in the background. Flickr Creative Commons/Kiah Ankoor

The ribbon was tied back together, and De Groot was arrested and fined five pounds, according to AG. Lang was then able to cut it himself. It might be because of De Groot's flamboyant show of loyalism that the presence of the Jersey contingent at that bridge's opening has been all but lost in Australia's version of events.

That wasn't the last time the Bayonne Bridge would be upstaged. An analysis of the Bayonne Bridge published by University of Bath undergrad RJ Pelly in 2009 notes that the bridge never received the same level of fame as the Sydney Harbour Bridge. Pelly posits that this was because it was "generally overshadowed by the completion of another of Ammann's creations; the longer and taller George Washington Bridge, which opened less than a month later."

The better-known George Washington Bridge connects Fort Lee, New Jersey, with Manhattan's Washington Heights. Getty Images

The Bayonne Bridge was still admired by those in the know, though.

"Although it may have failed to stand out in the public eye against the surrounding New York monuments," Pelly continues, "the bridge was immediately recognized among academic circles as a work of structural art, and awarded the 'most beautiful steel bridge' prize by the American Institute of Steel Construction in the year of its completion."

The Bayonne Bridge also offers something that most other bridges of its size do not: sidewalks for pedestrians. It's the only major bridge in Staten Island that allows use of its walkway, according to SILive.com, although Wikipedia says the walkway will be closed until about 2017 while the bridge is lifted.

What Bayonne doesn't have, though, are the stairways going over the bridge, found on its twin in Sydney and in many a vacation photo.

Australian Football League coaches pose for a photo while crossing the bridge. Getty Images

The Sydney Harbour Bridge also has concrete pylons on either side of the arch, which were included, according to Wikipedia, only to "allay public concern about the structural integrity of the bridge." They now house CCTV cameras, venting chimneys, and truck and vehicle storage.

Although these bridges appear to be so similar, only one looms large in the culture identity of its home city. Blogger Dominic Ambrose puts it this way:

"The Sydney Harbour Bridge is centrally located, a major artery and a major conduit for the economy of that city. It is a symbol of the city and valued enough to be well maintained and kept in the public spotlight. The Bayonne Bridge, on the other hand, is almost unknown to most New Yorkers and New Jerseyans. Connecting two perennially depressed areas, it has never really reached its potential (a second roadway, though planned, was never deemed necessary) and it has slipped into the shadows, rusting away at the periphery of New York Harbor."