The Silent City is the base of operations of the Silent Brothers. It is an extensive and complex city of levels and chambers so vast and deep underground. Found on the two upper levels of the city are its archives and the council chamber, where the Soul-Sword is kept and normally hung above the Speaking Stars. Beyond this are several other levels kept mostly a secret from and off-limits to non-Brothers.
At the lowest depths of the city are a series of levels that holds the necropolis of the Shadowhunters—the graveyard, ossuary, and mausoleums—where the bodies of those who died in battle are buried, entombed, and sometimes burned and used to fortify the City's marble arches; those who died of other means, such as suicide, are not accepted in the City and are instead buried in other places, including Idris.
On the very lowest levels are the prisons of the Silent City, known to hold both the dead and the living. Here are several jail cells, where the worst and most dangerous of Law-breakers and wrongdoers guilty of great crimes are confined and incarcerated, whereas those guilty of lesser violations are kept in Alicante, or in the keeps of Institutes. Some criminals are simply kept there before they are deported to Idris to stand trial before the Council. Sometimes, it is also used as a holding cell for those they need in the city overnight.
Much like the Adamant Citadel, the Silent City can be reached through one of a number of entrances scattered around the world. The Silent Brothers, and occasionally Iron Sisters, use this to their advantage to quickly travel between distant places to be rapidly deployed where they are needed. However, because of the secrecy of the Brothers with their city levels, regular Shadowhunters are not permitted to do so by tradition and Law.
Apparently, the largest single witchlight crystal in the world can be found in the Silent City. Standing at thirty feet tall, it is in the form of the Angelic Colossus, a triptych of Raziel with the Mortal Instruments. It guards and lights the entrance to the Silent Brothers' living quarters. Despite its fame, it is also rarely seen by anyone other than the Silent Brothers.
The chamber where the Mortal Sword is kept is a square pavilion, at the center of which is a black white-veined, basalt table where the Silent Brothers often gather around, while the Shadowhunter(s) they are addressing stands in front of them, on a larger black marble square on the ground engraved with a parabolic design of silver stars—aptly named Speaking Stars. The Mortal Sword is hung on the dark wall by the Speaking Stars. The pavilion is sometimes called the pavilion, or the great square, of the Speaking Stars.
The floor in this room is made up of red and bronze tiles. Each corner of the pavilion is marked by a spire of carved bone, and the room is lit by torches held by onyx holders along the sides of the square.
Interrogations with the Mortal Sword for truths can take place in this pavilion.
The Silent City was initially built around an anonymous cave in Idris, where David the Silent, the first Silent Brother, witnessed the ritual sacrifice performed by a Greater Demon that horrified him and made him a Silent Brother. With the help of the Iron Sisters, the cave was exorcised, and the beginnings of the Silent City was built.
The actual construction of the city took roughly four hundred years to attain its current size and reach. According to David's records, it began as a cavern of worked stone beneath Idris, consisting of a small council chamber, a small area that served as their living quarters, and a graveyard. Back then, before the Silent City could be considered a city, it was called the Silent Cloister.
The Silent Brothers and Iron Sisters continued to excavate the caverns, and the Cloister expanded over the years. Their living quarters, archives, laboratories, gravesites, and the council chamber, then known the Sword-Chamber, expanded and were moved and separated into different levels.
The first two entrances to the city outside of Idris were built around 1300: one in what is now the city of Bangalore, in southern India, and one in the city of Heidelberg, in what is now southern Germany. Both were created to allow Silent Brothers access to the extensive research materials in those cities. The Silent Brothers also began to recruit for their ranks among the mundane monks and scholars who either lived in or traveled to those cities for wisdom.
By 1402, Council records referred to the Cloister as "That Great City, whose levels we know not and whose secrets the Brothers keep in Silence." In 1471, the prisons of the Nephilim were moved from an outbuilding of the Gard in Alicante to the deepest levels of the City in 1471. By 1536, the council chamber was completed and opened to Shadowhunters.
The Silent City was where the furniture in the Dark House was taken to and kept for investigation. Some time after, some Enclave members went to the Silent City for the cremation of those that perished in the battle against Mortmain's automatons and de Quincey's vampires.
The same year, Jessamine Lovelace was taken to the city for questioning and kept in one of their holding cells, where she engraved the letters "JG" in her cell. She was visited by Jem Carstairs and Tessa Gray. Jem later moved to the city after becoming a Silent Brother.
In 2007, Clary Fray was taken to the Silent City to have her mind examined by the Silent Brothers. She was taken to the council chamber, and she stood on the Speaking Stars, and even bled on it after injuring her arm. Here, they discovered Magnus Bane's signature in the blocks on her mind.
Weeks later, Jace Herondale, then thought to be the son of Valentine Morgenstern, was temporarily held within the confines of the Silent City's jail cells under orders from Inquisitor Herondale. He was kept there overnight, and he was in the cells when Valentine came to steal the Mortal Sword. He had the Demon of Fear Agramon with him, who murders several Silent Brothers present. Clary, Alec, and Isabelle later arrive at the city as the first responders to the distress signal that was sent. The older members of the Conclave later arrived and examined the scene themselves.
Even later, Jace was again brought to the city after Jace began receiving troubling nightmares from Lilith. He and Clary were interrogated, in the Speaking Stars pavilion, about the nature of the dreams, and they were forced to share the events that took place on the shores of Lake Lyn weeks prior. Jace was kept overnight, with plans to redo his protection spells. Jace was kept in the same cell where Jessamine carved in her initials. Jace left the city before the spells could be performed on him.
- The Silent City was inspired by the Catacombs of Paris.
- In the Mortal Instruments film and TV adaptations, the Silent City has only been called "the City of Bones".