June 20th marked the start of the summer solstice, a moment that draws thousands of people from around the world to the ancient Mayan ruins at Chichen Itza, Mexico, to see a phenomenon that appears each year – a sun shadow of a serpent descending from top of the site’s main period. What many visitors don’t know is that much of the modern understanding of the ancient Mayans is rooted in the work of a Ukrainian-born academic from the Soviet era. Marcus Harton narrates this report from Olga Pavlova in Moscow. Camera: Ricardo Marquina Montanana and Luis Ramirez