Spawn

The Cage
The area within 100 blocks of spawn (0, 0) was originally known as The Cage by the original creator. The dimensions of The Cage go from 100 100 to -100 -100. It is known for its cage like lava cast, taking many buckets of lava to complete. Below the ground level (64) many caverns exist, with stairways leading to ground level. Obsidian highways were created from 0, 0 out in each of the four directions to 100 blocks.

Inner Spawn
All of spawn is a desolate place where few resources exist, no passive mobs spawn and few trees if any can be found. The area is either a dry desert, with some rivers remaining, and some ocean. Lava casts have sprung up, and deep caverns have been carved into the terrain.

Outer Spawn
Beyond the curtain wall at 500 blocks the world starts to become more normal, however as players have joined and the world matures resources such as wood will become ever more scarce close to spawn. Passive mobs can spawn beyond the curtain wall, and the highways continue out into the wilderness.