Mendev has relatively few traditional dungeons that have not already been plundered, thanks to a century of crusaders motivated both by piety and by greed. One little-touched location, however, dates from the First Crusade, when crusaders began construction on a fortress on the high ice of the Crown of the World to command the extreme northern frontier. Icerift Castle was abandoned when only partially complete, as it was decided it would be too difficult to resupply and reinforce. When the workers and garrison were to return home, crusaders sent to escort them discovered all had been slaughtered and their hearts torn out, without evidence of demonic taint. The native Mendevians blamed the slaughter on the legendary wendigo and the site was placed under anathema and stricken from crusader records. Fell rumors persist of what lurks within.
Sources: Pathfinder Chronicles Campaign Setting