For those who have not completed Xenoblade Chronicles X, this page may contain spoilers regarding the plot. Discretion is advised.
O'rrh Sim Keep is a landmark in Xenoblade Chronicles X. It is located in Cauldros, within the O'rrh Sim Castle Ruins. It can be accessed from the larger of the two doorways at O'rrh Sim Gate (once it is opened), or by infiltrating the O'rrh Sim Castle Ruins.
There are several gated passageways weaving through the O'rrh Sim Keep, but only the center counts as the landmark itself. It is normally devoid of enemies, except during the main story.