Physically conjoined but separately sold upon construction, the lives of paired buildings (ones that share a common wall) can diverge dramatically as this photo series poignantly illustrates. In various cases, one half of the duplex is occupied by squatters, filled with trash, burned out by a fire, boarded up, simply deserted or even entirely demolished.

Camilo José Vergara was born in Chile, resides in New York and is famous for documenting urban decay and city slums through text and images, but his Paired Houses set from Camden, New Jersey, tells a particularly powerful tale of times past and present.

This approach epitomizes a theme common to his work, which frequently focuses on showing change over time. Like twins separated at birth, these dual buildings (once mirror images of each other) are uniquely illustrative of change. They are found particularly often in Camden, a place with a long history of struggling against decline.

The common theme: buildings that share a party wall. For the unfamiliar, ‘party walls’ are not as festive as they may first sound. These are simply the shared partitions between buildings that are structurally contiguous – a common phenomena in densely-built areas. This joint element ties homes and other structures almost inextricably together – some of these share stairs, porch roofs and other architectural elements as well, all hard untangle.

Once abandoned, things tend only to get worse for the half still occupied. The other side may be used for anything from sleeping to drug use and dealing. Infestations of vermin on one side can cross back over as well. In many instances, the best-case scenario is to tear down the decaying half, like separating one conjoined twin to save the other.

While photo shoots can be meticulously staged, sometimes the best shots come with an element of surprise – particularly in the chaotic context of cities like New York an London.

Architect by training and photographer by professions, Daniella Zalcman took a series of photographs before leaving the largest city in the United States for the largest city in the United Kingdom, overlaying them secondary exposures in the latter city.

The results are predictably unpredictable – a mix of juxtapositions ranging from smooth transitional gradients to sharp spatial contrasts, capturing street art and sidewalk scenes as well as broader city-scapes and edge conditions.

In the end, many of the most jarring compositions defy the brain’s desire to organize a coherent narrative, like a tip-of-your-tongue memory or a slowly-fading dream, an effect reinforced by the gritty texture and grainy quality of the images themselves.

More on the artist, who has also since launched a Kickstarter project for this set: “Daniella Zalcman is based in NYC where she works as a freelance photographer for the Wall Street Journal. Born in Washington, DC, she graduated from Columbia with a degree in architecture in 2009. Other clients include The New York Times, the New York Daily News, Vanity Fair, Esquire, Sports Illustrated, Saatchi & Saatchi, National Geographic, Wired, and The Nation.”