The massive Cathedral of Avacyn lies in Thraben, the largest city of Innistrad. It has three wings and a network of cloisters, courtyards, outlying schools, and forges. There are well-kept gardens and substantial training grounds for cathars (holy warriors). Outside of Thraben, churches are quite rustic, constructed from rough planks and often containing only a single room. The Cathedral is opulent by comparison.

The grounds between the wings form a triangular courtyard that is locked from public view by high walls. Most people don't know the courtyard exists. Only the most powerful bishops are permitted to set foot in it. The Cathedral's structure symbolically divides the wealthy and poor of the world. Each class has its own designated place to worship:

  • Chapel of Noble Peers. The opulent, gilded chapel that is reserved for the high levels of clergy and titled members of society.
  • Midvast Hall. The larger, less opulent hall for ordained fellows and lesser clergy.
  • Common Cloisters. The covered corridors along the edges Midvast Hall where commoners stand during worship. There are only certain holy days when the commoners are permitted to enter the Old Cathedral.

At first glance, the courtyard resembles an ornate garden with stands of fruit trees and gold-and-white flowers that are cultivated with painstaking care. At the heart of the garden, the trees fall away, leaving a view of a curious object: the Helvault.

The Helvault is a huge silver mass that stands at the precipice inside the courtyard of the Cathedral of Avacyn. Its surface is rough and unrefined, and thin veins of dark mortar branch across its surface.