Tower of London

Her Majesty's Royal Palace and Fortress, more commonly known as the Tower of London, is a historic castle located in London, on the north bank of the Thames. Although conceived as a residence for royalty, it has served a host of other functions, most prominently that of a prison.

In 1868, Master Assassin Evie Frye infiltrated the Tower of London to assassinate Templar Lucy Thorne.

Reference

 * Youtube - Assassins Creed Syndicate: Evie Frye Hands on Preview - Gamescon 2015