In 1262 the wise King Alfonso X, against the will of the Celanova monks, built a royal town on the site of the uninhabited fort of Baronceli that until that point served to determine the terms of Pazos, Verín and Mixós. It was named Monterrei and became a fortified urban area or “alcaçaua”, a name that it keeps until this day. It was royal property and a capital municipality in the area until the year 1432.
In the first half of the XIV century the town had a new wall and fortification constructed over the main town square that served as a residence to the Zúñigas, Ulloas and Acevedos when they took over the lands. They reformed the parish church and established a Franciscan convent, built extra walls and new houses that had streets with different names. They constructed a shelter “where the poor is taken in and the orphans are raised”.

It had two unique entrances, Arrabal or San Francisco (to the North) and Porta do Sol (to the South East). Its inhabitants were stonemasons, butchers, carpenters, ironmongers, cobblers, a lawyer, a surgeon and two merchants. Additionally, the town had clerks and notaries, as well as military (soldiers, squires and knights) directed by a mayor. During the XV century Monterrei was a political and symbolic centre of the lord’s manor, with a military, political and religious purpose. It celebrated a weekly market and a monthly festival, but it didn’t achieve to rival that of Verín, that had a bigger population and commerce. The town was the subject of litigation between the Zúñiga and the Ulloa families. Diego López of Zúñiga and his son Juan (1458-1474) converted the castle into a Renaissance style palace, constructed a well and improved the walls.
In the year 1482 Sancho Sánchez of Ulloa, Count of Monterrei and Lemos, built a new Tower Keep. The new construction, visible throughout the whole area, would be the new symbol of power in the area. In1491 Francisco of Zúñiga became the Count (†1501) by ruling of the Catholic Kings, frustrating the pretensions of Sancho of Ulloa.
At the beginning of the XVI century the King sold the town to the Compostelean archbishop Alfonso of Fonseca for ten million maravedies. The intention of the prelate was to hand it over to his grandson, Alfonso of Acevedo and Zúñiga († 1559). Under his government they founded the college of the society of Monterrei, and in doing so they reactivated the economy of the town and undertook numerous projects. Count Alfonso of Acevedo was buried in Monterrei and in his memory the Jesuits composed texts written in Latin, Greek, Hebrew, Castilian Spanish, Italian, Portuguese and Galician.

The ordinances of the town from the XVI century mention the goods that were object of commerce at the festival of Monterrei: wine, fish -fresh and dried- meat, oil and candles, fruit, poultry, game, eggs and cheese. The laws paid special attention to the candles, bread and meat, legislating by weight. Monterrei had the jail house, located at the door of San Francisco, where “there are usually many and great delinquents, for being here the head of state”.
At the end of the XVI century Count Gaspar of Acevedo travelled to America to serve as viceroy of the New Spain and Peru and the decline of the town began. The Portuguese War of Independence (1640-1668) provoked the construction of the watchtower and new defensive structures around the existing medieval structures, equipped with doors and strongholds where cannons were installed. Half way through the XVII century the fortification was passed over to the Duke of Alba. At the beginning of the XVIII century, coinciding with the War of Succession, they built a barrier that divided the town from the Jesuit College, the cistern and the bastion. In the year 1735 a new war with Portugal forced a remodelling of the walls, converting Monterrei permanently into a military fortress. In time of peace the medieval bastion wall was used by the military governor as a vegetable patch, leasing the land for that purpose. In the decade of the 1750s the Franciscan convent had 32 clergy men (27 of those were priests), 13 Jesuits (9 priests) and 2 presbyters dedicated to St Mary of Grace. Half way through this century a military report defines the castle of Monterrei as a “garrison for invalid soldiers”. In the town at that point lived near to 300 inhabitants, among those there were 6 cobblers, 4 stonemasons, 2 barbers, 1 postman and 11 bakers (5 exclusively)
In 1764 they constructed the watchtower and focused on the construction of a fort on the high point of Esculqueira or of San Salvador, but we don’t know if the building works were ever finished. The remains were still visible up until the middle of the XX century. In 1767 King Charles III issued the expulsion of the Jesuits from the territory of the lord manor. The two lay employees of the chemist kept their jobs, but the college fell into decay, being attended by only 5 teachers. The college of the Franciscans takes over and gives classes of philosophy, art and theology. At this time the town had 487 inhabitants and Verín had 503. At the beginning of XIX century, during the War of Independence, Soult, Marshal of Napoleon, occupies the castle, forcing the surrender of the Marquis of Romana. Then, he marched towards Portugal. In the year 1811 Monterrei ceased to be the capital of the county, disappearing with the mandatory creation of councils established by the Constitution of Cadiz. The granting of the festivals to Laza (1816) and Cualedro (1818) resulted in a major blow for Monterrei, which previously had held a monopoly.
The confiscation of Mendizabal in 1834 left the town without the Trinity Hospital and also without the Franciscan convent of 44 Franciscans (among them 4 teachers and 11 scholars), who lived and gave classes in the Jesuit building, upon finding that their own had been ruined since, at the very least, the year 1823. Half way through the XIX century the council of Verín reused the stones of the old Jesuit College to construct houses and pavements. The paved floor of the temple served to pave the parish church of Verín. They also dismantled the old Franciscan convent. In the year 1857 Monterrei had 220 inhabitants that lived in almost 50 houses and Verín with 1429 thanks to its location and attractive commerce.