Blackthorn Hall, previously known as "Chiswick house", is a residence of the Blackthorn family. It is located in Chiswick, just outside London proper. In the 1800s, it was a property of the Lightwood family and was their country home.
The manor is a massive, looming structure with towering walls and gates. It is made of white stone which have since been blackened by years of rain and neglect. It was built in the Palladian style, bearing a strong resemblance to classical Greek and Roman temples or a small castle with its soaring pillars, multiple staircases, strong, symmetrical lines and columns holding up an arched portico in front of a set of massive double doors made of metal. The Blackthorn family, a circle of thorns, symbol is stamped into the metal front doors and on the tops of columns. It is surrounded by vast grounds that stretched to the edge of a meander in the Thames River. The property is surrounded by a high fence, tipped with sharp points, made of the same metal as the doors of the house, and the only entrance is one rusty gate built into it.
A courtyard with a long gravel road, once flanked by trees, led up to the house and had a circular drive in front of it. Stone paths then spread out from there, leading through a network of what used to be gardens before the home was abandoned. After 1878, the high hedges of the Italian garden twisted together and formed a maze. The ichor from the death of a demonic worm on its soil seeped into the soil and left a mark.
When the property was still cared for, particularly in the 1870s, low hedges ran alongside the paths, while high hedges covered the formal gardens. It included an Italian garden, the circle lined with statues of classical heroes and figures of myth, great historians and statesmen, and Greek and Roman poets and playwrights such as Venus, Caesar, Herodotus, Thucydides, Aristotle, Ovid, Homer, Virgil and Sophocles. It also had a wood-and-glass greenhouse with a cupola on the roof, a circular black ornamental pond, marble benches set around it, and a large folly shaped like a Greek temple and made of plaster.
As of 2012, only a single statue—one of a man in a toga—remained on the grounds. The gardens have become littered with wildflowers and untidy hedges, though evidences of its previous beauty were still around.
One path that wound around the side of the house leads to the wing that contained the ballroom. At the end of the path is a tall, narrow entrance, with a strange symbol carved into the door, that leads to a hallway and a long, narrow staircase that leads to the ballroom.
The house is glamoured to appear like a pleasant dull-looking private park.
The inside of the house itself, particularly the main wing, opened into a grand entryway. In the 1870s, the entryway's floor was designed with alternating squares of black and white marble. It had a massive chandelier, high windows, long corridors with blue walls and dozens of gilt-framed etchings, and a massive curving staircase that led further up into the manor.
The grand ballroom had a great crystal chandelier shaped like a spider. The walls were dark blue, and the room had French windows running along the side, opening into arches of curved stone balconies, looking out over a view of the gardens, as well as the river and the city. During the masquerade ball thrown in 1878, automatons lined the walls like decorative suits of armor, wearing the livery of the Lightwood household and an ouroboros over its left breast.
The library is a big, hexagonal room lined with bookshelves and oil paintings of great ships of wars. The walls were painted dark blue in 2012, and it had a marble bust of Homer atop a stone column and a big desk with several drawers. In the 1870s, the library served as Benedict Lightwood's office or study. The room was decorated with heavy curtains, green wallpaper, a Persian rug, and a desk guarded by a guardian demon. Its wallpapers were ruined by Benedict during his last stages of astriola, where he had written sentences with large letters with his ichor.
The other rooms have furniture covered in drop cloths, its windows boarded to protect the glass and boxes stacked in the halls.
In July 27, 1878, Benedict Lightwood threw a secret masquerade ball in the mansion to impress Mortmain. The party was attended by several demons and a number of Benedict's Nephilim friends. Nate Gray also attended the event and invited his "wife", Jessamine Lovelace. Tessa, Changed into Jessamine, Will, hiding behind his mask, and Magnus Bane, called by one of Camille's subjugates, came uninvited.
Approximately three months later, Benedict moved the household from Pimlico to Chiswick. There, he locked himself in his study for two weeks and underwent the last stage of his demon pox, transforming into a demonic worm. The demonic Benedict then escaped into the garden, devoured their servants and Rupert Blackthorn, and was later killed by the Shadowhunters of the London Institute. Much of the Italian garden was destroyed in the skirmish.
After Benedict's shameful death, the manor was confiscated by the Clave, until some years after, Tatiana Blackthorn—Benedict's daughter—managed to get the house back. In 1903, Tatiana and her daughter Grace moved into the house.
In September 2012, Ty, Livvy and Kit went to Blackthorn Hall in a quest to find clues about Annabel Blackthorn's whereabouts and found an aletheia crystal, inside one of the carved, plaster eye sockets of Homer's bust in the library, that contained memories regarding her from the early 19th century.