Purim is not over yet!
In Jerusalem Purim is celebrated today, the 15th of Adar.
Why?
In the times of Esther and Mordekhai, the Jews of Shushan asked the King for an additional day to fight against their enemies. The King granted their petition so the Jews of Shushan fought against their enemies on the 13th of Adar and on the 14th of Adar, and celebrated their deliverance on the 15th of Adar. While outside of Shushan the Jews celebrated their deliverance only on the 14th of Adar.
The Megila distinguished between walled and unwalled cities (Esther 9:18-19) saying that the Jews of the provinces, who live in unwalled cities, celebrated Purim on the 14th of Adar. While those who live in Shushan, a walled city, would celebrate Purim on the 15th of Adar.
The second Bet haMiqdash was already built by Zerubabel, but at the time of Purim, Jerusalem was still unwalled. The walls were erected in the time of Ezra and Nehemia, approximately 30 years after the events of the Megila. Jerusalem --the eternal capital of the Jewish people-- would have had a status inferior to Shushan and other walled cities in the world. Thus, in honor of Yerushalayim the rabbis established that the cities that were walled in the days of Yehousha bin Nun would be given automatically the status of "walled cities", and therefore, in Yerushalayim, Purim will be celebrated on the 15th of Adar.
Since then, in Jerusalem and its surroundings --every village from where one can see Jerusalem-- Jews read the Megila and observe Purim today. According to some opinions the city of Tiberias, in the north of Israel, is also considered a walled city. Tiberias has walls, but only on some parts of the city. But the Kineret lake --a natural fortification to the city-- is seen also as part of the walls of the cities.
WATCH
"Celebrating Purim in Tel-Aviv, 1932"