The Hejde Arsenal is a facility seen in Armored Core 4, first appearing in the mission "Barbe-Bleu."
Located south of Włocławek in Poland, the Hejde Arsenal is a research and development facility owned and operated by GA Europe. The facility itself is a series of of transport tunnels connected to large docks where behemoth-class weapons are designed and built. It is well defended by TYPE-DULAKE and ZENIGAME Normals.
It is here that the prototype Behemoths intended to carry the Sol Dios cannons were created.
It appears in the mission Barbe-Bleue, where Anatolia Raven's is contracted to defend it from a terrorist invasion. It later reapears in the mission Internal Purge, where GA America hires the Raven to destroy the Sol Dios Behemots prototype and retake the facility. The final fate of the Hejde Arsenal is unknown.