The overarching theme is to challenge the viewer's assumptions. Through each image, he seeks to examine the "thin line between the ugly and the beautiful; between the ordinary and the extraordinary; between chaos and order; between reality and abstraction."
Talking to CNN, Najjar says he only discovered photography four years ago -- and even then, at the behest of his mother.
"She registered me and my brother at a course her friend was running. The professor needed another two or three students for the class to go ahead, so she was helping her out," he says. "It's typical of the Lebanese mother, very present in her children's lives -- I was 37!"
He arrived at his first class a complete novice, but with what describes as the inherent ability to "sense when an art piece is good."
Najjar set out trying to treat his traditional camera as he would that on his phone, opting to use unconventional angles and the square aspect ratio found on Instagram. Whilst he developed his technical abilities, a clear focus began to develop in his output.
Najjar says he "was obsessed with architecture straight away." Drawing on constructivism, Parisian avant-garde and MC Escher, Najjar's work is all about finding art in architecture," describing his subject as a "playground for abstract photography."
"In Lebanon," he says, "we don't have very exciting architecture, but I always say it's not about what you see, but how you see it."
Uploading the results to Instagram, Najjar's clean lines and crisp shadows soon captured the attention of one of the app's curators, who asked to feature his photography online. A swell of support soon followed.
His first show, "Lines, Within" in 2012 -- for which Najjar had to teach himself how to develop his own photographs -- was a runaway success, with nearly all of the 32 displayed works selling. A nomination for the prestigious Prix Pictet arrived shortly after. In 2014, he exhibited at the prestigious Paris Photo.
Today he rises at 5 am at the weekends to capture his images, driving to nondescript locations.
"I try not to show the surroundings of the buildings," Najjar says, arguing it helps emphasize his photography's abstract qualities. The effect deprives the observer of context, creating an "anonymous message" to be decoded. Najjar believes the presence of people in his images is important however, as it provides "a certain scale and warmth to the architecture."
His methods still raise some eyebrows around Beirut. Najjar often struggles not only to convince security guards that he's not a spy, but that the locations he visits are worthy of his lens.
"The common and the ugly may not be as boring as we think it is," he contends.
Najjar, who holds a PhD in finance law and has been in practice since 1996, describes his unlikely second career as "a dream... like I'm wearing the shoes of someone else. It's a fun thing for me to do, because it's always such a challenge to get the image I want."