Flavius Claudius Julianus became ruler of Rome in A.D. 361 upon the death of his uncle Constantine. He favored Judaism over Christianity and sought to rebuild the Jewish Temple
as polemic against Christianity (and Jesus predictions that the Temple would be destroyed). Jewish religious authorities acquired the necessary building materials, but an earthquake intervened and destroyed the building materials. Julian died a short time thereafter and was succeeded by the Christian emperor Jovian, putting an end to Julians favoritism towards Judaism and the Jews.1
Thus, Julians Temple failed to materialize in history.
1 Randall Price, The Coming Last Days Temple (Eugene, OR: Harvest House Publishers, 1999), 99-100.