Westminster Abbey

Westminster Abbey, formally known as the Collegiate Church of St Peter at Westminster, is a large gothic church located in Westminster, London. It is traditionally the place where British monarchs are crowned and buried.

In Toaru Majutsu no Index, the abbey is also a magical facility.

Principles
The abbey leaks a large amount of magical energy, which allows certain magicians close to it to hide their use of magic.

Toaru Majutsu no Index SS: Necessarius Special Admission Test
Arlands Darkstreet and his subordinates from the Dusk Waiting to Awaken used the large leakage of magical energy from the abbey to hide themselves during the cabal's theft of the Necronomicon.

Queen Elizard later visited the facility in order to use the leyline link to send information from the British Museum to the damaged Pound Economy to speed up the recovery.