The Great Temple is a temple opened by activating 5 of the many Great Temple Shrines.
The gate is a large arch with five braziers above it. when one shrine is activated, a flame of the same colour of the cristal activated is lit in the brazier (Magically). Climing over the gate is practically suicide, as a variety of physical, psychological, and spiritual attacks bombard you all at once. This is deactivated when the gate proper opens. The gate opens when all five braziers are lit.
The interior is a single room with the temples guardian inside it (who, at first, seems like a giant armored statue). You and the guardian proceed via elevator to a battle arena and must face off. Fail, and you are taken out from the temple, with all braziers extinguished (meaning you have to start all over again). Win, and you gain a set of Magic armor, a copy of the set the guardian has, but shrunken to a human-sized figure.
In IW "canon"Edit
Goldas gained a set of the armor after beating the giant statue with the Neo forms of his weapons. He has since stopped using the armor.