In the Book of Genesis, the two evil cities that God destroyed with a rain of fire and brimstone (sulfur). Before the destruction, God sent two angels in the form of men to advise all good men to leave the evil towns. God's messengers found only one good man, Lot, whom they transported from Sodom to the countryside with his wife and daughters, warning them not to look back. When Lot's wife, not heeding the warning, looked back, she became a pillar of salt.
Note: sodomy was supposedly practiced in the wicked city of Sodom.