Marylebone Church

Marylebone Church is an Anglican cathedral located in the Marylebone Road in London.

History
During the mid-19th century, a particular headstone of the graveyard in Marylebone Church was used as a signal by the British Assassins, specifically Ethan Frye and the Indian Assassin Jayadeep Mir.

Every evening, Jayadeep was required to check the headstone's position: upright signifies no messages, leaning right with danger and left as a meeting. During one of his checks, he witnessed five men harassing an old woman in the churchyard. He immediately locked them into combat and saved the woman who was named Maggie.

Reference

 * Assassin's Creed: Underworld