The Jedi Tower amidst the Jedi Temple complex
The New Jedi Temple was a Jedi facility built upon the remains of the Jedi Praxeum used by the New Jedi Order during the Sith Crusade. Following the destruction of the previous temple in 66 ABY by Sith forces, the Jedi Order realized that any new temple that would be made must be capable of defending itself. And so, in 189 ABY, following the formation of the Jedi Autocracy; construction of the New Jedi Temple began. Zeferi, head of the Jedi Order made sure that it had the defense capabilities necessary to defend itself from any warship that the Sith had created, including the fearsome Decreto-class Super Star Destroyer.
Although considered a "temple", the facility was in actuality a massive complex capable of sustaining up to 500,000 people. The entire facility was dominated by the central Jedi Tower, which housed the Jedi Council. During the early 230's ABY the historian at the temple was Tai painj.
The temple, although intact as late as the Dark Age, was apparently abandoned by the Jedi during and in wake of the Zao tenj War.