A view of a portion of the Great Wall located northwest and north of Beijing showing the walkway to a fortified tower position. The construction of the wall started in the 7th Century BC by the first Emperor Quin Shui Hunag Di. It is 25 feet high and nearly 25 feet thick in places, the original wall, 1500 miles in length, took ten years to complete. In 1368 AD the Ming Dynasty continued construction for 200 years and it now is over 3750 miles in length. Exact Date Shot Unknown

Chicago citation style
Department of Defense. American Forces Information Service. Defense Visual Information Center. 1994-. A view of a portion of the Great Wall located northwest and north of Beijing showing the walkway to a fortified tower position. The construction of the wall started in the 7th Century BC by the first Emperor Quin Shui Hunag Di. It is 25 feet high and nearly 25 feet thick in places, the original wall, 1500 miles in length, took ten years to complete. In 1368 AD the Ming Dynasty continued construction for 200 years and it now is over 3750 miles in length. Exact Date Shot Unknown. 1986-10-01. Retrieved from the Digital Public Library of America, http://catalog.archives.gov/id/6506127. (Accessed June 18, 2018.)
APA citation style
Department of Defense. American Forces Information Service. Defense Visual Information Center. 1994-, (1986-10-01) A view of a portion of the Great Wall located northwest and north of Beijing showing the walkway to a fortified tower position. The construction of the wall started in the 7th Century BC by the first Emperor Quin Shui Hunag Di. It is 25 feet high and nearly 25 feet thick in places, the original wall, 1500 miles in length, took ten years to complete. In 1368 AD the Ming Dynasty continued construction for 200 years and it now is over 3750 miles in length. Exact Date Shot Unknown. Retrieved from the Digital Public Library of America, http://catalog.archives.gov/id/6506127
MLA citation style
Department of Defense. American Forces Information Service. Defense Visual Information Center. 1994-. Retrieved from the Digital Public Library of America <http://catalog.archives.gov/id/6506127>.
Note: These citations are programmatically generated and may be incomplete.