Western side of Ballcourt
"Among the other works of Yukom ? Tok are the remodeling of Structure XIII and the construction of the ball court marking the transition between the first and second half of the Late Classic, as deduced from the date corresponding to the year 731 inscribed on Stela 66, which was broken into four parts and used as construction material at the corners of the ball court."
Ramón Carrasco V., "The Metropolis of Calakmul, Campeche", in Maya. Rizzoli: NY (1998)