Entitled: "Armillary sphere at exedra, Meridian Hill Park, bounded by Fifteenth, Sixteenth, Euclid & W Streets, Northwest, Washington, District of Columbia, DC." Meridian Hill Park is a structured urban park located in the Washington, D.C. neighborhood of Columbia Heights in the United States. The park was designed and built between 1912 and 1940. In 1804 President Jefferson had a geographic marker placed on this large hill. Centered exactly north of the White House, this marker helped to establish a longitudinal meridian for the city and the nation. An armillary sphere is a model of objects in the sky (in the celestial sphere), consisting of a spherical framework of rings, centered on Earth, that represent lines of celestial longitude and latitude and other astronomically important features such as the ecliptic. In astronomy, the geocentric model (also known as geocentrism, or the Ptolemaic system), is the superseded theory that the Earth is the center of the universe, and that all other objects orbit around it. Ptolemy was an Egyptian polymath, who made studies in astrology, astronomy, geography and mathematics. Photographed by the Historic American Buildings Survey, December 15, 1965.