Today is Jerusalem Day (Yom Yerushalayim in Hebrew). The holiday, observed according to the Hebrew Calendar on the 28th of the month of Iyar, commemorates the reunification of Jerusalem during the Six Day War of 1967.
The days leading up to this event were tense; the Israeli Chief Rabbinate proclaimed a day of fasting and prayer, while the JNF pledged "to telephone every Jew" in the U.S. for financial support for border settlements (used here in a different context). You can read JTA’s reports from those dates here and here. It wasn’t declared a national holiday by Israel in November 1978, although it was first observed in 1968, initially planned by Mayor Teddy Kollek as something of an "internal" celebration" in deference to Arab neighbors.
One JTA headline from today’s celebration reads "3,000 police on patrol for annual Jerusalem Day March." In an interesting coincidence, one of our earliest records of a march in Jerusalem was a rally to protest British policy in 1939, which drew 3,000 women.
For two different perspectives on how Jews should relate to Jerusalem today, read these op-Eds by Nathan Diament, director of public policy at the Orthodox Union, and Rabbi Jill Jacobs , executive director of Rabbis For Human Rights-North America.