The courtyard was created when Amenhotep III built walls on either side, closing off the second and third pylons. Seti I began the murals you see and his son Ramses II finished them during his reign. The raised relief of Seti's carvings is more beautiful, but also takes a great deal more time to complete. Ramses was such a prolific builder that, of necessity, his carvings are done in the simpler but less aesthetic sunken relief. But both Pharaohs left us examples of temple ritual, detailed accounts of their battle exploits, and scenes depicting the relationship between Pharaoh and the gods. In fact that's Pharaoh kneeling in front of Amun on Seti's wall there.