A plan of the city of Washington from 1790. The lat/long figures on the map shows a longitude of 0 degrees 0 based on the Washington Prime Meridian passing through the Capitol. "This city was laid out by Peter Charles L'Enfant, who published his plan 'projected in pursuance of an Act of Congress, passed 16th July, 1790, establishing the permanent seat on the bank of the Potomic.'" (- Winsor, 1888) The original city plans called for a city 10 square miles and centered on the Capital building.