Designed in the 1830s, Omonia Square quickly became one of the major squares in the city. Originally named the Palace Square, it was later changed to Otto Square. Following the ousting of King Otto, it was symbolically renamed Omonia Square (Concord Square).

Today, many major roads lead from the square to places like Pireos, Panagi Tsaldari, Agiou Konstantinou, Athinas and Stadiou Street.

The square and its immediate surroundings gradually acquired their current appearance following World War II, when many major additions and renovations were made.