The World Of Silo Explained

WARNING: The following contains MAJOR SPOILERS for Wool and other Silo trilogy booksApple TV's sci-fi drama, Silo, explains 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, set to have a total of four seasons. Three seasons in, the Apple TV sci-fi series has already covered a lot of ground from the books while adding some of its own original lore to the mix. Arguably, some of the original aspects even make the series better than the books.

Despite covering many major arcs from the original book trilogy, however, Silo has still left a lot of questions unanswered. While many key mysteries surrounding its world have partly been resolved, others have an air of mystery around them. Based on the story in the books and the series, so far, one can still fill in the blanks and draw some intriguing speculations.

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. Silo season 3's ending arc even features a disturbing flashback scene that shows how a nuke goes off in Georgia close to the silos.

What's Outside The Silo?

The Surface World In Silo Is A Deadly Wasteland, Or Is It?

The inhabitants of the central Silo 18 are made to believe that the world outside the silo is deadly and poisonous, which is true. When people 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 air outside.

Throughout seasons 1, 2 and even 3, characters firmly believe that the world outside in Silo is truly as hostile and post-apocalyptic as it is shown on the main screen in Silo 18. Previous seasons even established that the cleaners' visors on their suits were manipulated to show them a deceptively pleasant, verdant outside world.

Towards Silo season 3's ending, though, a twist reveals that the outside world might be safe after all. A flashback scene reveals how Silo 17's people had successfully escaped their underground bunker before being shot down by drones controlled by Silo 1's leadership.

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

Image via MovieStillsDB

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

Image courtesy of Apple TV

The reveal of who created the silo is not 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.

Even the show reveals a similar origin story for the silos, with a few minor changes. Donald's name is changed to Daniel in the series, but his contribution to the construction of the silos remains equally significant.

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. She soon discovers through her travels that there is more than just one silo.

As revealed in the show and the books, there are a total of 50 silos. Almost anyone who has tried to leave them has seemingly been executed by the people of Silo 1. While the show is yet to explore what exactly happens when people step outside, it remains a dangerous fate for all characters.

Silo Seasons 3 Reveals The Origin Story Of The Silos

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

Credit: Apple TV

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 explores Shift's story.

Unlike the second book, however, Silo season 3 does not entirely unfold as a prequel. Instead, it goes 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 that is yet to be fully explored is nanobots. In the source material, an overarching 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. While Silo season 3 has hinted at how a nuclear war might have triggered the end of the world, there is more to the story than meets the eye.

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 TV 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 portrayed in 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 TV 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.

Silo season 3 drifts significantly away from the books as it changes the fate of characters like Bernard while making the ones like Camille a crucial part of the story. Even Juliette’s whole memory loss plot only happens in the Apple TV series. Going into season 4, Silo will likely move further away from the source material while still staying true to its main essence.

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  Rebecca Ferguson

  Juliette Nichols

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  Robert Sims

In a dystopian future, men and women reside in a vast underground silo governed by strict regulations, believed to shield them from the hazardous world above. The series delves into the complex social order within the silo and the mysteries surrounding their subterranean existence.