4 Av

c 447 BCE- The silver and gold that Ezra and his followers brought along to build the second Temple was weighed.  (Ezra 8:26-27)

c 444 BCE- Nehemiah, the leader of the Jewish people who had returned from dispersion in Babylon, began to repair the broken walls around Jerusalem. Portions of this rebuilt wall can still be seen today. The repair process took 52 days and was completed on the 25th of Elul.  (Nehemiah chapter 3)

1944- The Lublin concentration camp was liberated by the Russian army.