Old Naval Observatory

At twenty-third and E Street in Northwest Washington, D.C., the Old Naval Observatory served as the United States Naval Observatory from 1844 to 1893 and became a major center of astronomy, navigation, and timekeeping. Under Matthew Fontaine Maury and later James M. Gilliss and Admiral Charles Davis, it produced wind and current charts, sailing instructions, and precise time signals distributed by telegraph. Its Great Equatorial telescope, funded in 1870, was the world’s largest refractor when installed and enabled Asaph Hall’s 1877 discovery of the moons of Mars. After malaria forced the observatory’s move, the campus housed a succession of federal scientific, medical, intelligence, and naval offices.

Washington, District of Columbia · United States