Abandoned resorts around the Salton Sea. Salton Sea was created by accident in 1905, and saw massive development starting in the 1920's, resorts and marinas popped up all over. But having no outlet (all water which comes in ultimately evaporates) and fed primarily with agricultural runoff and prone to flooding, the water turned toxic by the 60's and mass fish kills turned the place into a stinking cesspit and guests and owners alike packed up and abandoned everything rapidly. It's not only known for the gorn of decaying buildings but the alien landscape of cracked salt-encrusted, dead earth and isolated pools of unnatural green-colored water.
Abandoned nuclear missile silos, often full of vintage equipment, and partially flooded.
Centralia, Pennsylvania, abandoned after an invasive coal mine fire undermined much of the small town and flooded it with high levels of carbon monoxide. Inspiration for Silent Hill. In reality, the town was never a big settlement and today most of the abandoned buildings have been demolished and disposed of in an orderly fashion, but there's still all the city block roads, some huge, cracked, smoking upheavals in the ruined Route 61 highway, and various black, smoking cracks in the ground surrounded by death, as the trees and foliage killed by the heat and gas drop all around and into them. A few longterm holdout residents defied the evacuation and continue to live in the town, which lacks any functioning stores or businesses.
Most examples are very large, very durable purpose-built buildings which could not effectively be retasked once they outlived their initial purpose, and have been too expensive to tear down. e.g. asylums (mental health isn't conducted this way anymore), sanatoriums (which were for long-treatment of tuberculosis), hospitals (based on obsolete technology), boarding schools (which are rare nowadays), factories based on obsolete products or manufacturing methods, and workhouses/poorhouses (good riddance).
Sometimes gorn is reversed. Adam Hats factory in Dallas lay derelict for decades, but then converted into trendy, high-priced hipster lofts without compromising its vintage exterior, which may explain why these structures aren't torn down.
Abandoned Six Flags New Orleans. Hurricane Katrina left it under 4-7 ft of brackish water for over a month, leaving most buildings and all ground rides total losses, even though superficially they appear intact. All abandoned amusement parks are inherent examples of this trope, as the dissonance of its joyful, cheery purpose is consumed alive by weeds, sun fading, and rust is readily apparent in almost any photo.
Many pictures of the Dust Bowl show tremendous gorn, the most amazing being cars and farm equipment more than half-buried in deposited dust; they appear to be melting into the earth itself.
Post nuclear-meltdown Chernobyl was one of the best real-life examples of this trope.
The nearby town of Pripyat is similar, but more in an eerie and deserted way. (Particularly with the new funfair that had just been built before the accident.) The animals seem to like the situation though...
As well as for tourists, Pripyat has become a destination for researchers from a variety of disciplines including ecologists and civil engineers, as it serves as a real-life example of what happens to a city after it is abandoned overnight (what species move in first, what materials degrade fastest without maintenance, etc.).
Post-WW2 Hiroshima and Nagasaki probably take the title in that category.
In fact in several older movies that involved the atomic bombings, stock Arial footage of Tokyo was used instead of those of Hiroshima or Nagasaki, because the Tokyo was more destroyed looking.
Major disasters such as hurricanes, earthquakes, mudslides and volcanic eruptions. See the photo galleries The Other Wiki has for Hurricane Katrina, the Great Haitian Earthquake, Armero, and Pompeii.
The endless footage of the collapse of the Twin Towers in the days and weeks after September 11th, and the pictures of the WTC site between the attacks and the clearing of the rubble.
Post-WW2 Warsaw. It's so damn impressive that they managed to rebuild it almost completely, even expanding it.
All firebombed European cities after WWII as well as some Spanish villages and cities after the Spanish Civil War.
For the first ten years after the eruption, the northern slopes of Mt. Saint Helens in Washington. Hundreds of square miles of blasted, gray wasteland covered in burned-out trees and rivers choked with ash and tree trunks. Even today, comparing the lush forests nearby to the colorless desert at the base of the mountain is rather sobering.
Any place there has been a recent forest fire.
One famous example, the Bitterroot Forest Fire. The scene is horrifying and tragic, however the photo a journalist took is disturbingly beautiful.
Many places in Japan are starting to look like this after the 2011 earthquake.
Heck, many places in Japan looked like this before the 2011 earthquake. Gunkanjima is a Scenery Gorn tourist attraction.
The great Soviet Union, when it was still great, had a tendency to build massive structures in a unique function-over-form styling (or lack thereof). Then it wasn't great anymore, money ran out, and they stopped building stuff that looked like it came out straight from Command & Conquer. More importantly, a large amount of the existing structures and the small cities surrounding them were abandoned, and now they are a favourite target for adventurous photographers. Witness the gorn.
Dixie Square Mall in Harvey, Illinois, which rotted away for over three decades before finally being demolished in 2012 and is most notable for being the mall from The Blues Brothers (it was already abandoned even then, hence why they had no qualms of trashing the place).
Fort Ord, an abandoned military base on the Monterey Bay, full of old beige post war buildings now boarded up and being enveloped by nature.
A small example: in 2005 someone managed to strand their Mercedes on 90 Mile Beach in New Zealand when the tide came in. Tour buses would stop by it for the next year or so while it slowly disappeared into the sand.