Ruins

Ruins are structures that spawn in the overworld. They are unique to a mythology. They serve as an early game source of cultural currency, that can be used to craft the portal igniters necessary to access mythological dimensions. They are found in biomes which most accurately correspond with the climate of their respective mythology's culture:

Norse:

 * Tundra
 * Rivers
 * Frozen rivers

Greek:

 * Plains

Egyptian:

 * Desert

Aztec:

 * Swamp