The original manuscript of the book from 1283 is kept in the Real Biblioteca del Monasterio de San Lorenzo de El Escorial (Escorial Monastery Library) in Madrid, Spain. It is an illuminated manuscript with beautiful paintings of games and players. Another manuscript copy, made in 1334, is kept at the Real Academia de la Historia (Royal Academy of History Library) in Madrid, Spain.
The book consists of ninety-seven leaves of parchment, many with colour illustrations, and contains 150 miniatures. The text is a treatise that addresses the playing of three games: a game of skill, or chess; a game of chance, or dice; and a third game, backgammon, which combines elements of both skill and chance. The book contains the earliest known description of these games.
More information here > https://en.wikipedia.org/wiki/Libro_de_los_juegos