Agrippa I, appointed by the Roman Emperor to rule over Judea, was pious and kind to his subjects. During his reign, the Jews began to prosper and live comfortably. The Sages of the time accorded him great respect.
Agrippa I started construction to repair, broaden and heighten the walls around Jerusalem. The Romans, wary of the Jews' rising prosperity, placed many obstacles in his way. Nonetheless, the wall was completed, though the finished product was not as magnificent as originally planned.
The 16th of Adar, the day when the construction commenced, was instituted to be a joyous day.
Today is the 3rd day of the "Triple Purim" observed this year in Jerusalem. Because the 15th of Adar falls on Shabbat, the Purim observances of "Mishloach Manot" (sending gifts of food to friends) and the festive Purim meal are fulfilled today in the city of Jerusalem (and the other ancient walled cities in which "Shushan Purim" is observed).
Solidarity with Jerusalem
"It would therefore be fitting and good, very good, that on this Sunday [when Jerusalemites celebrate the 'third day of Purim'] Jews everywhere should add in joyful activities: words of Torah (which 'gladden the heart'), gladdening other Jews with a feeling of love, and, if fitting or necessary, through sending mishloach manot and giving gifts to the poor...
"And through this all to further unite with Jerusalem, to which we turn daily during the course of every prayer: 'and they will pray to G‑d by way of the city that You chose'—chosen and given to each and every Jew forever, an eternal inheritance" -- from a public letter by the Lubavitcher Rebbe, 11 Adar II 5741 (1981).
Learn to be happy and you will find reasons to celebrate.
Approach a mountain with joy and you will climb over it.
You will break down every wall, you will melt every stone heart.
Happiness is not an outcome; it is a strategy for life.