Guilds (Nexia)

Various guilds exist in the world.

One tower in the Kingdom of Destiny contains a relief panel for each of the authorized guilds in the kingdom. These reliefs are created by a nominated Master of the Craft, and are created once a year, one at a time, determined by a calendar help by the Royal House. Legend has it that the panels tell the future, and many prophecies are said to be held in their simple depictions of guild life.

Reference
http://en.wikipedia.org/wiki/Campanile_di_Giotto