Tower of London

Tower of London (処刑塔 (ロンドンとう) ) is a historic castle in central London, England. In the Toaru Majutsu no Index universe, it is still used to keep prisoners despite being a tourist attraction.

Principles
Historically, the Tower of London was known as a place of blood, torture, and execution for prisoners. In modern times, it is open to the public for just under 14 pounds. The facility displays historical execution devices as well treasures of the Royal Family.

Despite this, the facility is still being used for its original purpose, in connection to magic side affairs, due to the blind spots in the building. Prisoners are still kept there and they are tortured or executed without hesitation as needed. If one enters through the normal entrance, these shadowy portions are completely unreachable, but if one enters through the secret entrance, one cannot escape them. These blind spots, unlike the areas where the sightseeing were held, are cramped and dark.

The Howaitotawā (ホワイトタワー), which gives the castle its name, is the area primarily used to contain magical prisoners. Much of the interior lacks windows, with various turns and stairs along the routes to the prison cells, which can lead to one's sense of direction and height fading away. There are various metal bar doors which block the corridors, with identical metal doors lined along the corridor leading to the cells. A typical cell in the tower, going by cell #087, is less than 6 square meters with a metal door bearing the cell number, a long and thin slot likely used to give prisoners food and water, and a small barred window positioned high on the wall. The only items in the cells are a worn mattress and blanket as well as a toilet. One of the torture rooms is located on the third floor, with a similar metal door and tall, small, barred window, as well as a restraining chair and various torture devices. Numerous doors, bars, walls and locks in the tower are reinforced with magic to provide additional strength, including the outer stone wall.

There are both temporary and permanent prisoners in the tower, and while most are kept imprisoned against their will, there are a few who stay in cells of their own will for various reasons (e.g. restraining themselves, as sanctuary from magic cabals out for their life, to free themselves from obligations of life, punishing themselves even if it means rejecting a pardon etc).

The ceremonial guarders are known as the Bīfītā (ビーフィーター) and are armed with long oak staffs which are not quite spears. A also reside at the tower,  and have a number of tales and superstitions surrounding them.

Curse scans of hair samples are used to verify the identity of individuals passing through the gates of the outer wall.

As well as acting as a prison, the Tower of London is also well known for storing many of the Royal Family's treasures, including the, mostly kept aside from the White Tower in the Jueruhausu (ジュエルハウス). Among the stored treasures is the core spiritual item which sustains the final barrier of the England-Londinium Fortress.

Seven Tools of the Tower of London
Kanzaki Kaori mistook the various tools of Misha Kreutzev as the Seven Tools of the Tower of London (処刑塔の七つ道具 (ロンドンとうのななつどうぐ) ) after looking at her. They are apparently famous interrogation tools used in the Tower of London. Since Kanzaki mistook the tools on Misha's person as like that of the Tower of London, it can be assumed that the tools include pincers, hammers, an L-shaped crowbar, saw, and a screw driver.

Background
The castle was initially constructed in 1066 during the, with the central tower, the which gives the castle its name, being built by  in 1078, and several expansions in the 12th and 13th centuries. It has served multiple roles over its history, including being a royal residence in its early years, an armoury, treasury, menagerie, public record office, and a home for the Royal Mint and the Crown Jewels, though its most famous role is that of a prison. It was used openly as a prison from the early 12th century, peaking in the 16th and 17th centuries, up to near the middle of the 20th century. In modern times, it is open to the public as a tourist attraction, though parts of the facility are secretly still used for its original purpose in connection to magical affairs.

Academy City Invasion Arc
Lidvia Lorenzetti was mentioned as being kept in the Tower of London.

Document of Constantine Arc
Stiyl Magnus, along with Agnese Sanctis, went to the tower to interrogate Lidvia Lorenzetti and Biagio Busoni regarding God's Right Seat. While Biagio remained defiant, Lidvia asked about what was happening outside. Stiyl said that she could make a guess on what was happening outside. She then shocked them by offering what she knew in exchange for having everyone that worked for her currently being held in the tower released.

Toaru Majutsu No Index SS: Kanzaki
It was mentioned that if Kanzaki took out Leivinia Birdway and moved her to the magical prison within the Tower of London, the world's safety would increase by a few percentage points.

Magic God Othinus Arc
Acqua of the Back commented about the second princess Carissa and the Knight Leader having both been held in the tower for their actions involving the British Halloween following World War III, having been temporarily released for the emergency situation for a preemptive attack on GREMLIN.

Return to England Arc
During the invasion of the United Kingdom by the Crowley's Hazards, in order to neutralize the final barrier protecting London, Aleister Crowley engineered Kamijou Touma's capture by the Knights of England so he would be sent to the Tower of London and be in a position to destroy the core of the barrier there. Touma was subsequently brought to the White Tower by the female knight and briefly imprisoned in cell #087.

After seeing Orsola Aquinas, who had been sent to help out at the tower by her fellow nuns so she wouldn't see the situation they'd be facing, and following an interrogation by Stiyl Magnus (who made sure to use normal restraints with any magical elements removed), Touma managed to escape with the help of Othinus, who had ridden a hawk up to the window of the torture room, and destroyed the spiritual item acting as the barrier's core.

The tower was left in a state of panic as many doors, bars and part of the outer stone wall had been destroyed by Imagine Breaker during Touma's breakout. While the beefeaters and other personnel tried to lock down the tower, perform headcounts and repair some of the damage, at least one prisoner tried to disguise themselves as a guard, but was exposed by Carissa after her conversation with Orsola and immediately restrained.

Around this time, the Knight Leader was on the battlefield outside the tower while Carissa and Acqua remained within it.