Regio Quinquaginta-Unus
The Regio Quinquaginta-Unas, more commonly known as the Regio, is the Armoury of the Blood Angels Chapter.[1]
Located beneath the surface of Baal, the vast complex holds weapons and relics too holy to be displayed within their fortress-monastery and various unique Standard Template Constructs that the Blood Angels have discovered, such as the Baal Predator. This measure is a defense against possible attack from hostile forces, both outside and from within the Imperium, and the Techmarines of the Blood Angels guard their relics vigilantly.[1]
Trivia
"Quinquaginta-Unus" is the Latin word for the number 51 - so "Regio Quinquaginta-Unus" would roughly translate as Area 51, a famous US air force base in Nevada that has been rumoured by some to hold extraterrestrial paraphernalia.