Construction began in 1880, with the blessing of the foundation stone by Jacinto Vera, making it the oldest building. Extensions and renovations in recent years have enhanced the identity of the building, combining the historical and the modern.

It houses the entire secondary school, 5th and 6th grade of primary school, as well as the offices of the administrative and support staff of the school. It houses iconic spaces of great historical and emotional value such as the Assembly Hall, the Library or the “Patio Rojo”, among others.

In 1967, a kindergarten for five-year-old children was created, and twenty years later, the preschool level for four-year-old children began. It was in 1992 when a house next to the Annex, commonly called “La Casita”, was conditioned; which would house these levels for many years, until it was finally necessary to move to a plot of land acquired on Canelones Street where today we find the Nursery, Preparatory and PreKinder 2 and 3 sectors. What we know today is the result of an expansion and reform carried out in 2015.

Known as Montserrat, this building was inaugurated at the end of 2023, being the scene of a variety of events, exhibitions and end-of-year events. In 2024, it opens its doors to courses focused on artistic expression such as theater, drawing, music, choir, among others, thus generating a . It has recording rooms, a photo production and editing room, a stage room and other rooms with greater flexibility depending on the proposed activity.

At the beginning of 1921, the school received a donation of land in La Floresta, which was initially called Pinar de San José, and later became Santa María del Mar. Almost twenty years later, in 1939, it began to be used for vacations and extracurricular activities. However, it was not until 1968 that the vacation chalet was inaugurated and thus the construction of the property that we know today began. The scene of retreats, camps, integration days and farewells has made Santa María del Mar an icon of the institution.