The Jewish holiday of Tisha B'av falls on Wednesday, July 26 until sunset on Thursday, July 27, 2023. Some call it "the saddest day" because it commemorates two major tragedies that happened thousands of years ago: The destruction of Solomon's Temple in 586 BC by Babylonians led by King Nebuchadnezzar II during his siege against Jerusalem; and then later when Roman legions under Titus sacked Jerusalem again after breaching its walls with battering rams and siege towers in 70 AD.