How do you open those doors at the Necrohol of Nabudis?

Any help? Thanks!!:D

It is part of a side quest. I suggest checking out over at GameFAQs for a step-by-step instruction on what to do. Unless someone here wants to give it up.

Basically, you need to collect three medallions for three Nu-Mou. One is found in Rabanastre's Lowtown, one is in the Archades Magick Shop, and the last one is with the regular save point in the Nabreus Deadlands.