Although Yom Yerushalayim, Jerusalem Day, commemorates the reunification of Jerusalem in 1967, its date fits in perfectly with the medieval Atbash cipher. According to Rabbi Chaim Richman of the Temple Institute in Jerusalem, the modern Jewish holiday always comes exactly one week before Shavuot on the same day of the week. The Atbash cipher, a technique for accurately calculating Jewish holidays, was first written about by Rabbi Yaakov Ben Asher (1275-1340), also known as the Baal HaTurim. Rabbi Richman in his weekly podcast on Arutz Sheva said that both Yom Haaztmaut, Israel Independence Day and Yom Yerushalayim are a perfect fit in the system.
Rabbi Chaim Richman, host of Israel National Radio's Temple Talk program explains the Atbash cipher and references other Jewish sources in a special Jerusalem Day podcast. To download the program click here.