Location from enders-game by Orson Scott Card
A spindle-shaped asteroid carved out by the Formics — humanity captured it, made it Command School, and hid the real war inside a simulator room.
Eros was carved out by the Formics during the Second Invasion as a forward operating base in the Sol system. After Mazer Rackham defeated them, the IF captured Eros and converted it into their highest-security facility — Command School, where the commander for the Third Invasion would be trained. The Formic architecture pervades everything: tunnels designed for four-foot workers make human adults stoop, and the alien geometry is a constant reminder that humans are occupying someone else's space. The simulator room where Ender commanded the real Third Invasion fleet is buried deep inside.
Spindle-shaped asteroid, 6.5km thick at narrowest. Surface absorbs sunlight and converts to energy. Interior: smooth-walled rooms connected by tunnels, all built for Formic proportions — low ceilings, rounded passages that make humans duck and hunch.
Also known as: Eros, The Asteroid