Under the Mansion, there is a secret underground cavern, referred to by the Nightwalkers as the "Night Cave". This is the true headquarters of the Nightwalkers, and is where they keep their equipment, and where they train.
The center of the Cave, where a very large computer is located. The computer is operated by V.L.A.D., who is constantly searching for problems within Washington. The computer is connected with the Night Watches, and instantly alerts the Nightwalkers of a threat.
Nathan Forge often uses this computer to hack and research, he also keeps a database filled with their supernatural allies and/or enemies.
This is where Nathan keeps his Dark Knight armor and here he does maintenance and the occasional upgrades to its systems.
This is where the Nightwalkers train, either for sparring or practicing new techniques with the latest in specialized equipment.
Hall of HeroesEdit
A space reserved for monuments, in case any of the Nightwalkers died. It was Nathan's idea, as he stated they should prepare for everything.
A special room arranged by Alucard especialy for the crystallized body of Leyla.
Salazar had stated multiple times that, though Lila is dead, she is always watching over them, and that her body has a secret power that will one day be needed.
It is where the Nightwalkers keep the trophies they have collected over time.
The Red RoomEdit
Also refereed to simply as "The Room", it is where Alucard stores the books, manuscripts and artifacts he has collected over the years. It is technically a vault, having titanium plated walls and a heavy door. Said door is usually hidden from sight, behind a plain stone wall. The inside is illuminated by red lights, hence the name give to it. In order to open the vault door, two keys are required: one with Alucard and one with Salazar.
Initially, the room was completely off-limits to all except Alucard and Salazar, due to the fact that many of the artifacts stored there have hidden, and sometimes deadly powers. As a matter of fact, Alucard has repeatedly stated that The Room is probably the most dangerous place in Washington... possibly America.
Unknown even to Alucard himself, there are 6 Immortal Fangs hidden amongst his other artefacts. So far, only four of them are revealed: the Cross Gun Fang, Chainsaw Dragon Fang, Omni Blade Fang and the Essence Fang.