The square located in front of the Parliament building is an iconic landmark of Athens. It dates back to the 19th century and boasts a fountain and several sculptures. It is set in the proximity of Athen's famous attractions and demonstrations are often held here. It is definitely worth visiting for changing the guards ceremony.
Wikipedia https://en.wikipedia.org/wiki/Syntagma_Square
Address (Unnamed Road), Αθήνα 10563, Greece
Coordinates 37°58'31.98" N 23°44'5.123" E