Castrojeriz or Castrogeriz is a locality and municipality located in the province of Burgos, in the autonomous community of Castile and León (Spain), the comarca of Odra-Pisuerga, the judicial district of Burgos, head of the town council of the same name and former head of the Castrojeriz judicial district.

It is a popular stop along the French Way of the Camino de Santiago[2] or The Way of Saint James, which crosses the city longitudinally for more than 1,500 meters.

In the 1787 Floridablanca Census it fell under the jurisdiction of a lordship with its proprietor being the Marquesa de Camarasa, with an ordinary mayor.

The village was established by Count Muño (or Nuño Nuñez), who defended the fort at the end of the ninth century against the Arabs.

There is a calvary which sports a Cross of Tau (Tau) instead of the Latin cross perhaps as a reminder of the Order of the Antonians who had a monastery and hospital on the outskirts of the town, where they healed and tended to the sick afflicted by St. Anthony Fire, called also the holy fire, a disease now known to be caused by ingesting a fungal parasite on rye.

The hospital was very important, because it was the headquarters of the General Commandery of the Order of San Antonio in the various realms of the Crown of Castile and Portugal, with over twenty dependent encomiendas (house-monastery-hospital).