The school was founded in September 1855 in Piraeus, the port city of Athens. The funds for the construction of the school were donated by Iakovos Rallis, the brother of the Mayor of Piraeus at the time, Lucas Rallis. The donation was subject to two main conditions: that only girls should be admitted in the school and that there should at all times a statue of Adamantios Korais, the great educationalist and linguistic reformer, be displayed within the school premises. In case of breach of the above mentioned conditions, the donation would be revoked and all the funds would be returned to the heirs of Iakovos Rallis.
The construction of the first building, which was located in the city centre, opposite the famous City Theatre, finished in the year 1857, when the school was inaugurated.
That building was demolished in the 1970?s and the school had been operating in various locations in the city centre up to September 2016 when Ralleio, at long last, moved to its home, a new environmentally friendly building of high aesthetic standards.