In TERA there are a few hidden locations above the altitude limit and far off of the area map. These locations grant special achievements, and all are marked by a billboard known as a Wall of Wordcraft. People who find these locations are able to place a message on this wall, and despite the large number of players in the game each Wall of Wordcraft has only been found by around 500 people. The number of people who have found every Wall is even lower, and the amount of notation and documentation on these locations seems rather low in the community, something rather strange due to the rewards received for finding these locations.
