Maethrillian

The Capital was the political center of the Forerunner Ecumene. It was a massive structure, exceeding the scale of even the Halo Installations.

Design Details
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.

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.

List of appearances

 * Halo: Cryptum