Empyrean is the capital of Eden and the military headquarters of the angel forces in Euclid. The ancient city is connected to Ezekiel's base of operations through a wormhole opened by Gabriel Alchemilia.
Vritra created a palace as a gift for Vassiliki. Angel architects were tasked with designing a massive city to surround Vassiliki's castle. Using demon slaves, this planned city would be partially built in the years immediately preceding the War in Eden. Modifications were made to Empyrean's extant structures to improve defense, but construction was postponed indefinitely upon declaration of war.
Xeren would lead a charge into Empyrean, accompanied by many of his demon army's greatest warriors. Refusing to allow his city to be destroyed, Vritra met Xeren as his army approached and challenged him to single combat. Xeren killed Vritra with Ahriman as soldiers of both armies watched in awe. The demon army began to cheer for Vritra's slaying when representatives of the Powers arrived to take Xeren away.
Years later, Alchemists Co. would begin experimenting with interdimensional travel. A testing facility was constructed in southern Thales for use in the Alchemilia Wormhole Project. A portal between Euclid and Eden was successfully created shortly after the demon invasion of Euclid. The angels took control of the facility, utilizing it as their primary forward operating base in Euclid.
Josephus, a legendary angel warrior, created a moat surrounding the perimeter of the Euclidean portion of Empyrean. He was able to accomplish this feat through Aegis-class reality manipulation, Josephus being a reincarnation of Vritra. The origin of his abilities are unknown to most, with the Nuyö-Dyavol Coalition officially considering the moat to be the product of forced labor by demon prisoners. Privately, Cicero suspects Josephus was an Aditya.
The moat would dry up shortly following its creation. A group of prospectors led by one Traian Pendleton began excavating the mineral deposits in the trench circa 240 TP. An angel patrol would take notice. After the prospectors remained in place for several days, the patrol made contact. Pendleton explained that they had no intention of breaching the city limits of Empyrean. The angels allowed the prospectors to continue excavation, provided half of all materials recovered were turned over to them.
Vassiliki's castle is the centerpiece of the portion of Empyrean in Eden. It towers over all of the other buildings in the city. The palace is composed of ornate materials, including those which are incredibly rare elsewhere on the planet. Vritra ensured that only those allowed by him or his wife could enter the castle. Few living beings besides the Powers and Ezekiel can still access the castle.
Empyrean was to be a grand city which could house millions of citizens. In effect, only a few hundred architects, slaves and military leaders ever took residence before Empyrean was near-abandoned by the exodus to Euclid. Less than three hundred angels remain in the city at present, prepared for the unlikely event of an evacuation from Euclid through the wormhole.
The wormhole created by Alchemilia Corporation remains in place. It is located at the base of Vassiliki's castle in Eden and near Ezekiel's headquarters in Euclid. The apparatus surrounding it has been maintained and enhanced by angel scientists.
The former Alchemilia Corporation Testing Facility remains structurally intact, although many of the objects contained within have been scrapped for parts. The Corporation insignia has been taken down and replaced with the heraldry of Josephus' Hussars. The building now serves as meeting place for the angels' military leadership. The personal residences of Ezekiel, his advisors and their families are nearby.
Josephus' Hussars, an elite unit of the angel army, are based out of Empyrean. Their barracks and training camp are located to the east of the military headquarters.
The defenses around Empyrean are designed to make entrance on foot impossible. The city limits are marked by fencing and watchtowers. Surrounding the towers is a minefield. Beyond the minefield is the Prospector's Trench. The northern half of the Trench can be accessed by any interested party, provided the angel overseers are given half of all materials collected. The southern side of the Trench cannot be accessed by humans under any circumstances.