The Dragon Temple is located in the Swamp, it is a large, worn down building where the Elemental Guardians reside. It houses the Pool of Visions and a training Dojo, and it sports a large terrace at the front with a view to the ocean.
The main part of the building is the Dojo. When not used for training, an enormous statue of Malefor occupies the room. Connecting to the Dojo is the exit out to the terrace, and on the opposite side is the way into the room of the Pool of Visions. In the same room, eggs were kept for safekeeping prior to the first attack. From that room, there are two doors leading out to either the swamp(aNB) or to the temple garden(tEN).
When Malefor was young, the temple was not a lone building, but surrounded by other tall thin buildings, presumably houses, and was part of a city like Warfang. There were significantly less mushrooms in the area as well.
After Malefor's return, the temple was torn from the ground and suspended above the volcano, reshaped into Malefor's Lair as a symbol of his dominance.
Pool of Visions
The Pool of Visions is used by dragons like Ignitus to see visions, dreams and memories of others. At the start of A New Beginning, it is shown being bright blue, and later a strong green, possibly due to algae after being unkempt for years.
The Legend of Spyro: A New Beginning
After the war between the Dark Master's forces and the Dragons, the Dragon Temple was overtaken by Cynder's Ape forces, but was reclaimed when Spyro eventually drove them out, accompanied by Ignitus and Sparx. It served as a shelter and home to the Guardians, and eventually Spyro and Sparx. In the prologue of the game, the dragon eggs were in the Grotto with the Pool of Visions.
The Legend of Spyro: The Eternal Night
The Dragon Temple appeared again as the current home for the Guardians, Spyro, and Sparx, and also a temporary shelter for Cynder before she left, blaming herself for what happened when she was under the Dark Master's control. The temple then came under attack, and Spyro battled his way through the grounds of the temple to get back to the Guardians. After driving off the forces of the Ape King, Gaul, the Dragon Temple was damaged during the surprise assault and wasn't seen again in the game after Ignitus sent Spyro off to the Ancient Grove where the Chronicler was supposedly hiding.
The Legend of Spyro: Dawn of the Dragon
During the three years before the events of Dawn of the Dragon, the Guardians lost their hold on the Dragon Temple while fending against the Dark Master, Malefor, who then raised the temple above the volcano as a symbol of his dominance, earning its name, Malefor's Lair. It was later destroyed when the Destroyer broke the world apart in a torrent of fire during the final battle between Spyro, Cynder and Malefor.