On 16 July 1212, a Crusader army made up of Castilians, Aragonese and Navarrese (but also French, English and Germans) confronted the army of the Almohad Caliph an-Nasir at the foot of the Sierra Morena mountain range. The Battle of Las Navas de Tolosa, as the battle is known, is considered the most important battle of the Middle Ages on the Iberian Peninsula and is a key event in the history of Spain. More than 800 years later, a group of archaeologists and specialists have begun an archaeological study of the battlefield. Is everything that has been said about the battle true? What secrets does the terrain hide? And, above all, what can we learn today about events that took place hundreds of years ago and that pitted tens of thousands of people against each other in the south of our country?