In the film El Cid fights for a Spain in which Moors and Christians can fight (sorry, live) together in harmony. In reality he was at one time happy to take work as a freelance mercenary, fighting against Moor and/or Christian alike. In fact the Emir of Zaragoza, who Cid captures and converts to niceness at the beginning of the film, was historically Cid’s employer during his freelance days.
The capture takes place under the walls of Ampudia Castle in Palencia province, a XV century castle which was in ruins at the time, and which has since been restored. Filming took place there on the 23rdMarch 1961 to shoot the scene where El Cid arrives at a Christian town that has been sacked by the Moors. The castle looms over the scene as El Cid shows that he’s just a simple man sent by God to teach solid values to everyone else in the cast