Later that year, during the Dark War, the Basilias was once again used after the battle at the Adamant Citadel. Jace Herondale and Brother Zachariah were taken there after Jace struck Zachariah with heavenly fire, along with other Shadowhunters injured during the battle with the Endarkened. While there, Jace caught a glimpse of Amalric Kriegsmesser, an Endarkened who was being studied by the Silent Brothers.
The Basilias is a large stone building with steps leading up to double doors. When open, the building is brightly lit by witchlight.
Within the Basilias are rows of white-sheeted infirmary cots. There is an arched ceiling painted with interlacing designs of healing runes in silver and blue. The floor is made of marble, and there are arched windows between each of the cots. The Basilias also has private rooms as well, all of them located in a narrow, white-plastered corridor.
- Only Shadowhunters are allowed to enter the Basilias.