Remiem Temple can be found the Calm Lands. Get a Chocobo and to the southeast side of it, just east of the entrance from Macalania Woods. There, you can find a Chocobo feather on the ground, which will prompt the Chocobo to flutter-jump over to Remiem Temple. A few details you can do before the airship is obtained are discussed in Remiem Temple, a sub-section of the Calm Lands walkthrough. This mostly discussed Al Bhed Primer Vol. XXIV, the Chocobo races, and the 30 Wings of Discovery.
Within the Temple itself, you can meet up with Belgemine. She is here to challenge you in a consecutive battle against her numerous Aeons - you’ll have to beat Valefor, Ifrit, Ixion, Shiva, and Bahamut in order. You can also fight Yojimbo and Anima as you get them, and the Magus Sisters after all this is done. They’re all easy battles, especially with the prowess you are given from teaching Aeons abilities. Just match up elements or go for sheer power with Anima. =P By the way, items are rewarded for winning:
- Valefor - **Four Lightning Gems** , or the Summoner's Soul if you don't have it; four Power Spheres thereafter
- Ifrit - 3 **0 X-Potions** , or the Aeon's Soul if you don't have it; five Mana Spheres thereafter
- Ixion - **10 Chocobo Feathers** ; eight Power Spheres thereafter
- Shiva - **60 Mega-Potions** ; six Star Curtains thereafter
- Bahamut - **Flower Scepter** ; eight Mana Spheres thereafter
- Yojimbo - **8 Shadow Gems** ; ten Power Spheres thereafter
- Anima - **60 Stamina Springs** ; ten Mana Spheres thereafter
- Magus Sisters - **40 Shining Gems** ; twelve Power Spheres thereafter
After defeating the Magus Sisters, you can opt to Send Belgemine, and in doing so earn the Moon Sigil .
As for earning the Magus Sisters? That’s a bit harder. You need two things. One is the Flower Scepter you can earn here. To earn the Blossom Crown , you need to go to Mt. Gagazet and capture every fiend there and within the cave. Then, after getting the Flower Scepter and Blossom Crown, you also need to get Yojimbo (see Cavern of the Stolen Fayth) and Anima (see Baaj Temple). Then you can return to Remiem Temple and go to the sealed door in the back to obtain the ultimate Aeons - the Magus Sisters!