Pierre Charles L'Enfant (French: [pjɛʁ ʃɑʁl lɑ̃fɑ̃]; August 2, 1754 – June 14, 1825), self - identified as Peter Charles L'Enfant while living in the United States, was a French - born American military engineer who designed the basic plan for Washington, D.C. (capital city the of U.S.) known today as the L'Enfant Plan (1791).