During the years the construction changed by modifications and additions, so that the evolutionary process reached the fullness at the end of the 18th century. In the mid-18th century the church, built in stone, had only one nave and three cloisters, of which the first was constructed with columns and carved stone arches, but the other two were made of wood with spaces for classrooms and offices for the friars. The building had a long and wide, splendidly carved wooden roof and covered with tiles.

In the second half of the 18th century the architect Ignacio José Balboa added the baroque side facade on the Mercaderes street to the building. The statue of Santo Domingo de Guzmán, the patron of the Order of Preachers, carved in stone, was placed in a niche over the side door that was topped by a semicircular arch. The statues of Saint Thomas Aquinas  and St. Peter Martyr, placed on columns, were guarding the side entrance. Saint Thomas Aquinas (1224-1275) was an Italian Dominican friar, immensely influential philosopher, theologian and the greatest thinker of the Scholastic School. He incorporated Aristotle’s ideas into Christianity. St. Peter Martyr (1206-1252) was an Italian Dominican friar that served as inquisitor. He was killed by an assassin and was canonized as a Catholic saint 11 months after his death, making this the fastest canonization in history. All the statues were in landscape proportions. The rest of the side facade looked clean and sober. Because of the unique composition of the side facade, the pristine main door, facing O’Reilly street door, was preferred by the faithful less frequent than the side door; maybe also, because it provided more comfortable and fast entrance and exit.

Another important addition was the dome with lantern that was dedicated to Our Lady of Rosary. The exterior surface of the dome was covered with bluish green ceramic slabs; a feature, that drew considerable attention. It was not a particularity of Cuban churches, but of Mexico. In the last quarter of the 18th century the distinctive feature of the building was its bell tower that was one of the highest in the city of the time. It was erected at the north side of the building and over the semicircular main door.

In the first half of the 18th century the Dominican friar that were concerned in the education system of the island, requested for the permission to start with the studies in their convent. At that time, children of wealthy families had to go Mexico, Santa Domingo or Spain to receive education. In 1721, the Dominican friars obtained the approval of founding an university in their convent, Convento de San Juan de Letrán, also known as Convento de Santa Domingo, by the bull issued by Pope Innocent XIII. Counts of Bayona had great support in this event. In 1728 King Philip V of Bourbon confirmed by a Royal Decree the establishment of the Real y Pontificia Universidad de San Gerónimo de La Habana in the renovated convent. This was the first university in Cuba and one of the first universities founded in the Americas. This date is accepted as the date of the establishment of the modern University of Havana today. Except the short period in 1762 in that the invading British army used the building as barracks, many children of wealthy families received education in the fields of laws, medicine, mathematics, grammar, theology and philosophy, attending the five faculties of the university until 1841. The prominent personalities of Cuban thought, science and culture that studied in this university are Felix Varela, Manuel de Céspedes, Francisco Vicente Aguilera, Ignacio Agramonte, Francisco de Arango y Parreňo, Tomás Romay, José Augustín Caballero, Antonio Bachiller y Morales, José María Heredia, Rafael María de Mendive, José Antonio Saco and Cirilo Villaverde.

By passage of time, the Dominicans lost their power, and finally also the possession of their property, so that they could not continue with the education that was their main activity as tutors. In 1841 their building passed into the hands of the state, and when the administration of the university was undertaken by the Spanish government, the university was called Real y Literaria in 1842. It was no longer a religious institution and changed its status to become a secular, royal and literary institution.

The Order of Preachers, also known as Dominican Order and its members as Dominicans, and in France as Jacobins, is a mendicant Order of the Roman Catholic Church, founded by Domingo de Guzmán (Saint Dominic) in Toulouse during the Albigensian Crusade, and confirmed by Pope Honorius III in 1216.

Domingo de Guzmán was notable for his learning and love of poverty. His Order had two characteristics: instead of manual labor, as practiced by the Cistercian monks, he required his friars to work with their minds by preaching and teaching. Thus, the Dominicans were particularly dedicated to preaching and excelled in the field of theology. Many members of the order took part in the Medieval Inquisition.