Star Wars Never Revealed The Jedi Temple's Biggest Secret
By the time of the prequels, the Jedi Knights had settled down at the temple on Coruscant—but surprisingly, Star Wars never revealed its biggest secret.

Star Wars tie-in reveals the biggest secret of the Jedi Temple, but the secret has yet to be explored in any real detail. Little by little, Star Wars is revealing the history of the Jedi Order. Luke Skywalker discovered the first Jedi temple on the distant world of Ahchtor, confirming that the Jedi developed far from the galactic core. Early Jedi explorers used the Force to travel across the galaxy, believing it would guide them to worlds teeming with life. The Jedi apparently settled in Jada for a while, claiming it as their own world.
However, the relationship between the Jedi and the Republic has changed and developed over the centuries, with the most important Jedi Temple being the one found on Coruscant. The Jedi Temple on Coruscant was built over an ancient Sith temple, a center of dark side power that the Jedi hoped would be controlled by their light. Claudia Gray's novel Into the Dark reveals that Republic-era Jedi Knights - centuries before the prequels - actually used this dark side spotlight . They would bring relics and artifacts to it, use the Force to remove their dark side, and store their power within the Fusion. they believe that then dissipated into the power of the universe.
The Jedi Used Coruscant's Force Vergence For Other Purposes

Star Wars #20 by Charles Soule and Marco Castiello reveals that the Jedi Knights used it for other purposes. In this issue, Luke unlocks the holographic record left by Master Yoda, and his mentor briefly describes the Force Fusion to him. "There are places where the Force is more concentrated," Yoda observed, "but these places can be dangerous. They are called rendezvous points and should not be explored without proper training and preparation. The Jedi Temple on Coruscant has Such one. Ghazan Living Sea, the other. And Jeddah." According to Yoda, these three planets are rich in the Force and can be used to peek into the fog of time and space.
Star Wars Issue 20 explores the Ghazian Sea of Life, revealing that Force-sensitives can immerse themselves in it to receive visions of the past and future. George Mann's recent audiobook, The Battle of Jedha, reveals Jedha's Force confluence, a temple full of kyber mirrors; the Jedi order Meditate before these mirrors and receive visions from the Force. Interestingly, the description in The Battle of Jeddah brings to mind similar visions experienced by Darth Vader As he meditates on his fortress on Mustafar, so there may be other divisions that could be used in this way - ones that the Jedi don't know about.
But the Force focus of the Jedi Temple is rarely seen, and there is no record of it being used in this way. It's possible that the Jedi had already discouraged its use by the time of the prequels; Yoda, in particular, came to believe that it was unwise for the Jedi to seek hallucinations, and they believed they should be allowed to happen naturally. This would certainly explain why Star Wars hasn't shown this aspect of the Jedi Temple on Coruscant yet.