An enormous cave carved out of a mountain, which is home to the annual Cave Eight Race, as well as an auction house.
The Cave Eight Race is an eight-hour endurance test, where vanship pilots are first given a random, broken down vanship that they must fix before the race begins. Then they fly for eight hours until midnight, circling a subterranean race course several times. The team that crosses the finish line first after midnight, or makes it the furthest before breaking down (assuming that no one actually finishes in such an event) is the winner. The time is kept by a gigantic hourglass that is turned over at the beginning of the race. Vanships used in this race - Horizon Cave Eight Race Vanship.
Later on in the series, the horizon cave is used as a training ground for special Vanship forces preparing to fight against the Guild. It is also here that Claus meets Ralph Wednesday's older brother and informs him of Ralph's death.
On the map of the race there are places with very interesting names, eg .:
- Jupiter ghost
- Isis temple
- Shiva temple
- Tower of Set
- White hill
- Junction symbol
- Tasmanian devil
And many others.