South side, from the Via Triumphalis

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https://commons.wikimedia.org/wiki/File:RomeConstantine%27sArch03.jpg
The image is under a Creative Commons License
Author: Alexander Z. (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/)], via Wikimedia Commons