Klafthmonos Square is the one with the most denominations than any other square in Athens. According to the original plan of the city of Athens in 1834, it was called "Aeschylus Square". Along with the "Koumoundouros Square" were symmetrically designed in a way that if they were united with an imaginary line they would create an isosceles triangle with the Royal Palace of the time.
Later on it was named "Nomismatokopio Square", which translates to "Mint Square" due to the Mint building located on the north side of it.
In 1838, however, it was renamed to "March 25th Square," a name that it kept for many years thereafter. The name was given because it was there that the first celebration of the Anniversary of the Greek Revolution of 1821 took place.
After this denomination, it was named "Republic Square", until 1878 when through a vignette of D. Kambouroglou's Estia magazine, it was given the title "Klafthmonos", which despite the changes that followed, was to become the most known denomination.
In June 1989 and on the occasion of the unveiling of the very popular sculpture of the three embraced people, the square was renamed again, for the sake of this sculpture in "National Conciliation Square". This name, however, never found use.
For the record, "Klathmonos Square" has a very interesting story behind its name. It was named so, because before 1909 the offices of the Ministry of Interior were there. In those years the public officials were not permanent. This resulted to the dismissal of non-permantent officials with every change of the government. They then gathered in the gardens of the square and mourned with tears (Ancient Greek:klafthmos) and begged for reinstatement.