'''''Santa Gadea''''' is({{lang-es|Iglesia thede nameSanta ofÁgueda}}) is a church dedicated to [[Saint Agatha]] in [[Burgos]], [[Spain]]. The church is famous in history and literature for being the site where Rodrigo Díaz de Vivar ([[El Cid]]) at the behest of the [[Kingdom of Castile|Castilian]] [[Cortes Generales|Cortes]], forced [[Alfonso VI of Castile|Alfonso VI]] to swear an oath that he was not an accomplice in the death of his brother, [[Sancho II of Castile|Sancho]] while he was besieging [[Zamora, Spain|Zamora]]. [[Romance XX|''Es el de la jura de Santa Gadea'']] [https://www.poesia-inter.net/indx0023.htm] is the most notable Spanish medieval [[Romance (heroic literature)|romance]] about this event.