The World Of Silo Explained

WARNING: The following contains MAJOR SPOILERS for Wool and other Silo trilogy booksThe Apple TV+ sci-fi drama Silo series explained a complicated world author Hugh Howey created through his acclaimed series of novels. Wool, the first part of the Silo book series, was written and self-published as an e-book by Howey in 2011, twelve years before the Apple TV adaptation debuted in 2023. Howey later released Shift and Dust in 2013 as extensions of the Silo universe.

Apple's Silo is based on the entire book trilogy, with at least one future season already confirmed to delve deeper into the later books. Accordingly, Silo involves complex and detailed world-building that demands further explanation.

Silo tells the story of a community that lives underground in a vertical safe haven due to the poisonous conditions of the outside world. The inhabitants of the silo believe an apocalyptic event centuries ago makes life on the surface impossible. The series stars Rebecca Ferguson as Juliette, who takes over as Sheriff after Sheriff Holston decides to leave the silo to learn the truth about the outside world.

While the series hasn't revealed much about the function and creation of the silo, the truth can be found within the Silo book trilogy for those who can't wait.

Where Are The Silos?

The Specific Location Is Mentioned In the Books

Based on the information provided in the Silo books, the silos are located in Fulton County, Georgia, just outside of Atlanta, USA. This can also be deduced by the English-speaking actors with American accents in the Apple TV+ series.

The exact location is also explored in the series, and even the Westernized themes of the underground society point to the implication that the silos are a part of the United States' territory.

What's Outside The Silo?

The Surface World In Silo Is A Deadly Wasteland

The inhabitants are made to believe that the world outside the silo is deadly and poisonous, which is true. When workers are sent out to clean the camera at the silo's surface, they are only able to survive for a few moments before ultimately suffocating and dying from the poisonous air.

This is because the suits that are meant to protect them from hazardous toxins do not protect them at all, meaning even those who keep their suits on aren't safe from the toxic fumes.

The world of Silo is also truly hostile and post-apocalyptic as it is shown through the main surface-level camera. Both Holston's and Allison's visors on their suits were manipulated to show them a pleasant, verdant outside world, but this was a deception.

Holston believed that Allison was right in thinking that the world wasn't really poisoned and that a beautiful landscape awaited them above. Once he took the helmet off, Holston realized that they had not been lied to and that leaving the silo was a grave mistake.

How Big Is Each Silo?

The Silos Are As Large As Four Empire State Buildings

The entire height of each silo is roughly 5,760 feet, which is equivalent to four Empire State Buildings stacked on top of each other. The social class systems within the silo are so distinctly divided due to the great distance that the bottom-level inhabitants would have to climb to reach the upper levels.

The walk would be especially tiring due to the incline and the number of stairs one would have to traverse. The lack of an elevator in the massive structure implies that the separation was deliberately designed to maintain a distinct caste system within the silo between the mechanical workers at the bottom and the authorities at the top.

How Many Floors Are There In The Silo?

The Last Surviving Humans Have Over 100 Levels Of Living Space

The silo extends approximately more than a mile deep into the Earth with 144 levels that are each 40 feet tall. The Apple TV+ series kept the same dimensions as the original silo in the book to capture the immense size of the underground civilization.

While some, including Mayor Ruth in Silo episode 3, may choose to make the trek up or down the silo by foot, it is typically only done on the rarest or most urgent of occasions. While it's possible to walk the full length, it would likely be exhausting.

Who Created The Silo?

The Silo Exists Because Of A 2049 US Government Project

The reveal of who created the silo isn't discussed until the second book Dust, which explains that a multitude of silos were ordered to be constructed by the United States federal government in the event of a catastrophic attack that risks the future of humanity.

Dust states that in the year 2049, Congressman Donald Keene was appointed to create the first-ever silo due to his expertise in architectural design.

Donald completes the project in 2052 by crafting an underground shelter system that consists of 50 individual silos. That same year, nuclear explosions took place on Earth which made the world uninhabitable.

What Happens When Citizens Leave The Silo

All That Awaits Outside The Silo Is Death

All that was known about leaving the silo was that people would ultimately die due to the poisonous air. Juliette becomes the first person who successfully manipulates her suit and goes to the surface with the necessary protection to explore the post-apocalyptic wasteland. Juliette soon discovers through her travels that there is more than just one silo.

There are at least 18 different silos all at various levels of civilization. The Apple series will likely unfold the events that bring Juliette to Silo 17, where she breaks in and finds out about an uprising that ended terribly for the inhabitants.

Hugh Howey's books Wool, as well as Dust and Shift, so far seem to possess the exact blueprint of how the Apple TV+ series Silo will play out. Although there is a possibility that the creator of the television series Graham Yost could change some key elements of the book trilogy, so far the show has stayed true to the plot of the source material.

Silo Seasons 3 Will Reveal The Origin Story Of The Silos

Silo's Season 3 & 4 Still Has Plenty Of The World To Explore

While Silo season 1 introduced the vast and complex post-apocalyptic dystopia created by Hugh Howey, season 2 explored the world beyond the central Silo 18. The second book in the series, Shift, is a prequel to Wool (upon which season 1 is based). Since season 2's ending is somewhat in tandem with Wool's closing arc, season 3 is exploring Shift's story.

Unlike the second book, however, Silo season 3 does not entirely unfold as a prequel. Instead, it is going back and forth between the past and the present to connect the silos' origin story to the present timeline.

A key element of the world of Silo to be introduced is nanobots. In the source material, the nuclear war was a response to the emergence of weaponized self-replicating nanotechnology. Without giving away too many spoilers, nuclear annihilation was seen as the lesser of two evils in comparison to the alternate nanotech-based apocalypse humanity nearly faced.

The key reveals, however, are less to do with the world and more to do with its history, since everything from humanity's future to the creation of the silos is steeped in intrigue and conspiracy by the time the original Silo books conclude. The more Silo season 3 progresses, the more it will seemingly explore these deeper story beats from the original books.

Changes Made From The Silo World In The Book

Apple Added Several Important Worldbuilding Elements

Like every attempt to bring a work of literature to the small screen, Apple had to make several changes to Hugh Howey's novels to make Silo better fit the new format. However, the majority of these changes were character-based rather than alterations to the world the story takes place in.

This will likely change as Silo continues, but season 1 managed to remain relatively faithful to Howey's books when it came to world-building aspects. However, there were still two key changes that the Silo show made to the world of the books — though, unusually, these didn't involve removing or changing pre-existing ideas, but adding in new concepts.

What's more, the main additions and changes to the world of Silo Apple made include some of the most important concepts in the show so far, which makes the fact they're not in the source material at all especially surprising.

Two of the most important unique concepts in the world of Silo are the mysterious illness known as The Syndrome, and the group of rebels known as the Flamekeepers. Both are being set up to be key plot points in Silo season 2 and beyond, which makes it incredibly intriguing that neither are in the books at all.

The rebellion about a century before the main story did take place in the Silo books too, but it's not an integral plot point. The TV show, on the other hand, works the rebellion into current events, especially with Juliette.

The Syndrome, on the other hand, is completely unique to the lore of the Silo TV series. Nothing that's even close to The Syndrome appears in the Silo books, with there being no mysterious health condition that's even hinted at in passing.

The Syndrome illness in the Silo TV show is one of the most intriguing worldbuilding aspects, as it stands to reason that living in an underground silo with no sunlight would have health implications.

It's likely that there will be more worldbuilding changes made from the books as Silo continues. Many characters and key events have also been altered already in season 1, but so far, the show has managed to keep Howey's vision of the world the story takes place in more-or-less intact.