Castle Acre Priory is located in the village of Castle Acre, Norfolk. Founded by William De Warenne in 1090 as a Cluniac monastery, it would have been subject to the abbot of Cluny and the priory at Lewes.

Originally the priory would have been within the bailey walls, but the monks were given the present site as the order expanded. At first the monks were probably given a small house in about 1085, beside the church of St Marys in the bailey; there would have only been about three or four monks at first and they would have carried out the cluniac routine as best they could. As the small building became too confined and less suitable, William II gave the monks land to the west of the castle. The building work began in about 1090. One of Williams charters reveals what he gave them, ' two orchards and all the plough land from the orchards to the castle'. He also provided the monks with a mason, called Ulmar, to work on the buildings. The construction of the church was slow, it was consecrated around 1146 - 8, with the west end being completed in 1160. The monks would have been living on the site by 1100, as soon as the east end of the church was completed. They lived in timber buildings until the priory was completed by about 1150.

By the mid 12th century, William III gave the monks more property while he re planed the town and built massive earth ramparts to protect the town from attack while providing security for the residents. This also allowed tolls and taxes to be collected.

The priory prospered, in 1140 it had property in 28 parishes in Norfolk, by 1291 it held at least 50 more as well as property elsewhere. These provided much of the priorys income, from rents, tithes and gifts to the parish churches it controlled. Additional charges were made for baptism and burials. The priory also made money from pilgrims wishing to catch a glimpse of the priorys relic, the arm the Apostle Philip. Four priorys were set up, between 1115 and 1160, all tied to Castle Acre priory which helped with income and added prestige and influence. The expansion of the priory, often took the monks into debt, what with the alms giving to the poor, maintenance of the monks and servants.

The monks were often audited by Cluniac Officials from the 13th century, mostly priors from other houses. These audits reported on the monks finances and behavior. Often the monks were critised for their behavior and actions, in 1265, they were found to riding about the country, eating and drinking indifferently in the houses of laymen and secular persons. Another strange report, in 1279, the 35 monks conduct was satisfactory, but the prior was found to be extravagant and eager to resign.

Tensions developed between the parent house at Lewes and the priory because of the behavior and actions of the monks at Castle Acre. Lewes was responsible to Cluny for the Norfolk monks but could not control them. In 1283 Lewes appointed a new prior, but he was met with armed resistance from the Norfolk monks and the Earl of Surrey who backed them. It was eventually settled by the Abbot of Cluny himself.

The priory had its ups and downs, suffering during the war with france in the late 13th century, booming in the later 14th century with improvements to the buildings. The late middle ages saw further embellishments and alteration to the buildings, because of fashion and increasing attention to comfort.

The 16th century brought the dissolution of the monasteries. In 1535, the priory was investigated to build a case against them, however false, charging the monks with self abuse, fornication and adultery. Castle Acre priory surrendered to the crown on the 22nd November 1537. Some of the monks may have become parish or chantry priests.