Maethrillian,[1] more commonly called the Capital, was the political center of the Forerunner ecumene. It was a massive structure that exceeded the scale of even the Halo installations.[2] It housed a population of one hundred thousand Forerunners, mostly high-ranking Builders and the Forerunner Council.[3] Trillions of ancilla served in the capital's metarchy, an enormous network coordinated by a Metarch-class ancilla.[2]


The capital was one of the oldest structures in the ecumene, being roughly 25,000 years old by 100,000 BCE.[4]

During the Forerunner-Flood war the Capital was attacked by 032 Mendicant Bias who had been persuaded into Rampancy by The Primordial. Mendicant Bias then fired Installation 07, eliminating the Ecumene Council and much of the Capital. By around 100,000 BCE, the Flood had nearly overrun the entire system where the Capital was situated.


The capital was composed of a series of perfectly circular "platforms" arranged in a spiral along a central rod. These platforms decreased in size toward either end of the rod, with the widest central one being approximately 100,000 kilometers in diameter. Each platform was covered with a "city" of structures and buildings,[2] whose gravity was controlled individually by buffer fields.[5]

The capital was home to the Council amphitheater, where the Forerunner Council engaged in debate on important matters. The amphitheater was suspended in midair, attached to the rest of the capital by bridges, anti-gravity gondolas, and individual lift tubes for each of the Councilors. During Council proceedings, the amphitheater would be decorated with display spheres showing representations of the twelve of the systems inhabited by early Forerunners, each carrying an epistle of the Mantle. Near the Council amphitheater there was a hallway with its walls decorated with countless spent slipspace flakes, some of which had also been built into sculptures.[6]



It was one of the most trafficked locations in the Ecumene, with constant security patrols, Sentinels and transports swarming around it.[2] Within five thousand kilometers of the structure, incoming vessels would be carefully screened by sensory fields and directed by hard light docking nets.[7] The capital's system housed multiple slipspace portals that linked to a variety of worlds, including the Ark.[8]


In the event of a large-scale attack, the capital could rotate its sections to assume a spherical shape, thus protecting the structures atop each platform from damage. It also possessed powerful energy shields and a large defensive fleet. If the capital metarchy coordinating the fleet was compromised, the fleet would splinter into individual squadrons, each having specific instructions on how to deal with an attack.[9]




  1. Halo Waypoint: Forerunners
  2. 2.0 2.1 2.2 2.3 Halo: Cryptum - pages 280-281
  3. Halo Waypoint (Xbox 360 App): The Universe - Events - Cryptum Glossary
  4. Halo: Cryptum - page 296
  5. Halo: Cryptum - page 304
  6. Halo: Cryptum - page 293
  7. Halo: Cryptum - page 283
  8. Halo: Cryptum - page 312
  9. Halo: Cryptum - page 311

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