The Box
From Wulfgard Wiki
The Box was Whisper's name for the building in Coronaria where she was trained by the Silent Messengers. A very old, unremarkable tower on the outside, it had no doors, and no windows save for those on the uppermost floors. The interior was similarly unadorned, with subterranean rooms beneath it, where the Assassins held meetings. The main purpose of the building was to train orphans abducted from the streets, teaching them to be a new generation of Assassins. After its presence and purpose was revealed to Imperial authorities by Whisper in 1116 AI, the building was breached by the First Legion and cleared of all its contents. The Assassins - who disappeared without engaging the Legion - abandoned it, never to return.