In May 1967, for the first time since the Holocaust, Jews were digging mass graves for themselves, expecting the worst from the coming war in which Egypt, Jordan, Syria, and 13 allied armies threatened to destroy the Jewish State. In the cool of the morning of June 7, Israel went from apocalyptic fear to the shofar of Redemption blowing, and the words crackling on army radio, “the Temple Mount is in our hands.”

As Yossi Klein Halevi tells it in his award-winning book, “Like Dreamers,” the thoughts of young soldiers “drifted into history,” realizing they would be “the first soldiers of a sovereign Jewish state in 18 centuries to enter the capital of the Jewish people.” Even secular soldiers kissed the Wall where no Jew had been allowed to stand in 19 years, and then they were on the Temple Mount and Jewish history was forever changed. In the grit of war, the 28th of Iyar became not just a holiday but a holy day, Yom Yerushalayim, Jerusalem Day.

In 1967, no one could have imagined that in less than 50 years Yom Yerushalayim (this Sunday, May 17) would fall on hard times. Once widely celebrated, it has almost disappeared from the communal map, not even listed on many Jewish calendars. Attempting a revival, Hebrew Institute of Riverdale is hosting a Yom Iyun (day of learning), celebrating “the heavenly and earthly Jerusalem,” celebrating Jewish unity on the anniversary of Jerusalem’s unification.

HIR Rabbi Steven Exler tells us, “Yerushalayim is meant to be a place that brings people together, opening our hearts to what’s possible in the world.” In that spirit, the event is bringing together a rare if not unprecedented (at least since the early post-war years) “diversity of voices, all kinds of shiurim [classes],” reflecting on Jerusalem’s significance “through art, history, religious significance,” with teachings and conversations aiming at “breaking down barriers.” Along with HIR’s Rabbi Exler and Senior Rabbi Avi Weiss, some of the participating groups will be Camp Ramah-Nyack (Conservative), Bnei Akiva (an Orthodox youth organization), the Sholom Hartman Institute, CLAL, AIPAC, the Jewish Orthodox Feminist Alliance (JOFA), Yeshivat Chovivei Torah, Yeshivat Maharat, the Drisha Institute, Mechon Hadar (an egalitarian yeshiva), and the UJA-Federation of New York.

The day will begin, says Rabbi Exler, with a Tefillah Chagigit, davening appropriate for a festival, including Jerusalem melodies, Hallel with a bracha (blessing), and a spiritual sense “that Jerusalem, as it is today, is absolutely a modern miracle.”

Rabbi Exler hopes people will take away an awareness that Yom Yerushalayim “deserves its own special attention” and that the day’s conversations and teachings reaffirm not only Jewish dreams and unity but Jerusalem’s “point of commonality between people who otherwise have religious and political differences.”

The event runs from 9 a.m. to 3 p.m., with prayers at 8 a.m. and will take place at Hebrew Institute, 3700 Henry Hudson Parkway in the Bronx. Admission is $45.