The site of Errew Monastery was donated by James Hardiman, the foundation stone was laid on the 21st of July, 1840 and a great number of people were present. Dr. McHale, Archbishop of Tuam was the leader of the ceremonies.

James Hardiman laid the foundation stone and placed coins of the day under it, the people of Errew helped with the building. They came in crowds and cut through a hill a 100 feet high.

Money was collected through out the country. Archbishop contributed £5.00 and Daniel O'Connell £1.00. The monastery school was opened in 1842. Brother Bernard McGarry and Brother Paul O'Donnell were the first teachers. It had two spacious class -rooms with a good map on the wall.

In April 1884, 260 children were attending the monastery school. The Brothers opened other rooms on the second floor. A great decline in the number of children attending occurred after 1884 because of new schools opening in the area.

As well as the primary school, Errew monastery also had a classical school. This was a centre of higher education mainly for the training of priests and teachers.

At this time Irish was regarded as the language of the poor. The brothers showed their students that Irish was a suitable language for business and study. James Hardiman lectured in the classical school occasionally. Among the students who attended the classical school were Archbishop Gilmartin, Bishop Higgins and Ulick Bourke.

During the Famine years 1846-1849 the brothers were very active in feeding the poor, Brother McGarry and Brother O'Donnell collected large sums of money in the United States for the relief of the famine victims.

With the money raised the brothers were able to provide a small meal for 400 children daily.

There are 22 Brothers buried in the Monastery cemetery. There is a sapper's mark on the gable of the Monastery. This mark was used to measure land.

The monastery closed it school in 1975 and the boys went to local girls national school.

A Bench Mark, known as a Sappers mark indicates the level above mean sea level. There is a Sappers mark on the North - west corner of the Monastery, on the front wall of the School, and on Deasy's bridge.

The mark resembles three points on a crow's foot.