Temple of Light

Appearing only in Ocarina of Time, the Temple of Light, also known as the Light Temple, is the resting place of the Triforce. It is the only known elemental temple that is not located directly within Hyrule. Instead, it lies in the very center of the Sacred Realm and is closely linked to the Temple of Time. The only way to access the Temple of Light is through the Pedestal of Time inside the Temple of Time. By withdrawing the Master Sword from the pedestal, a portal opens to the Sacred Realm, which leads to the Temple of Light.

Chamber of Sages
The Temple of Light, unlike all other temples, is not an explorable area. Only one of its rooms is visited: the Chamber of Sages, which is where the Sages meet.

After Link withdraws the Master Sword from the Pedestal of Time, his spirit is sealed away in the Chamber of Sages due to him being too young to bear the title of the "Hero of Time". Since Link's action opened the gate to the Sacred Realm, Ganondorf took this opportunity to gain access to the Sacred Realm, eventually reaching the Temple of Light and taking the Triforce for himself.

Seven years pass, and Rauru the Sage awakens Link in the Chamber of Sages now that he is old enough to be considered the Hero of Time. Rauru explains Link's fate and grants him the Light Medallion to add to his power, sending off the young hero to awaken the other five Sages so that they may add their might to Link and aid him on his quest to save Hyrule from Ganondorf's rule.

Though Link is not able to visit the Temple of Light on his own, he is always warped to the Chamber of Sages every time he awakens a Sage. Here, the Sage bestows their powers to Link in form of a medallion before returning to Hyrule again.

At the end of the game, after Link gives the final strike to Ganon and Princess Zelda calls upon the power of the Sages to seal Ganondorf away, Rauru along with the other five Sages appear inside the Chamber of Sages to send King of Evil into the void of the Evil Realm.

Theory
The Pyramid of Power in A Link to the Past is believed by some to be the [Temple of Light, due to its location in the Sacred Realm, its appearance in the game's prologue speaking of the Sacred Realm, as well as the large Triforce marking in the pyramid's main chamber (where Ganon is fought).

The Temple of Time of Twilight Princess is also believed to actually be the Temple of Light. To explore the Temple of Time, Link must enter a portal into what seems to be a parallel world. The portal is created with the Master Sword, also a key to the Sacred Realm. Thus, it is possible for this "parallel world" to be the Sacred Realm, thus making the Temple of Time the Temple of Light. Additionally, the dungeon is light-themed and is decorated with markings of the Light Medallion.

Trivia

 * The music in the Chamber of the Sages is a looped version of the music that plays when Princess Zelda tells Link the Legend of Hyrule earlier in the game.
 * It has been shown via emulation hacks (the debug rom) that the platforms in the background are, in fact, solid, and with aid of another hack it's possible to "visit" them. It is unknown whether this is a trace from the beta version of Ocarina of Time or just a glitch.
 * Considering its location in relation to the Temple of Time, the Temple of Light may be the dungeon Link encounters within the Temple of Time in The Legend of Zelda: Twilight Princess. This is supported by the many appearances of the emblem of the Light Medallion in the dungeon, even including on switches and the floor of the room where the Darknut is fought.
 * Strangely, in Twilight Princess, the room where the Sages are gathered has been shifted to the Arbiter's Grounds in the Gerudo Desert.
 * Despite not being explored, the temple still receives recognition as the "Light Room" in Ganon's Castle, this along with the effect of the Light Medallion still existing in Ocarina of Time's data leads Zelda hackers to believe that the Temple of Light was a dungeon in the beta of Ocarina of Time but was later removed.