Ancient historians and classicists typically cite ancient sources like this: [author] [title] [book #].[chapter #].[section/line #]. Your citation could thus read: Pausanias Description of Greece 2.13.7. If it helps, you can check the text via the Perseus Digital Library.

If you've been instructed to cite things according to Chicago Style, I would go with: Pausanias 2.13.7 in W. H. S. Jones (trans.), Pausanias: Description of Greece, vol. 1, Loeb Classical Library (London: William Heinemann / New York: G. P. Putnam's Sons, 1918), 319. However, I would verify it with the instructor first. :)