The Land Ruins are the centre of the Earth Elemental Disorder. They are located in Sandworm's Den.
These are the first ruins Evann's team visits, however, they have already been excavated by the Nortis Army and the team simply has to make their way down to the Spiritual Atrium to meet Colonel Kroitz and Specto. It is here that Kroitz explains the source of the Elemental Disorder and assigns you your mission to resolve it.
The only boss in this dungeon is a Minotaur (similar to the one in Grandia II).