Group manages the Great Lines of Earth category. These include markers, plaques or other objects that indicate one of lines below:
Five major circles of latitude:
1. Arctic Circle (66° 33′ 38″ N)
2. Tropic of Cancer (23° 26′ 22″ N)
3. Equator (0° latitude)
4. Tropic of Capricorn (23° 26′ 22″ S)
5. Antarctic Circle (66° 33′ 38″ S)
Equal latitude degrees:
Also look at http://en.wikipedia.org/wiki/Circle_of_latitude
Equal longitude degrees, except the Prime Meridian.
Other historical meridians, such as the historical Paris Meridian.