The Temple of Olympian Zeus, also known as the Olymppeion (Greek Ναός του Ολυμπίου Δός, or Naos tou Olimpiou Dios), is located in Athens, Greece. Although its construction began in the 6th century BC, it was not completed until the reign of Emperor Hadrian in the 2nd century. During the Hellenistic and Roman eras, it was the largest temple in Greece. It is located approximately 500 meters southeast of the Acropolis of Athens and about 700 meters south of Syntagma Square, the center of Athens.

The foundations of the temple were laid by the tyrant Pisistratus in 515 BC, but work was abandoned after the overthrow of his son, Hippias, in 510 BC. During the Athenian democracy, it was left incomplete because its scale was considered excessive. Aristotle cited it as an example of how tyrannies committed the people to large state projects, leaving them without resources to rebel.

Construction was resumed in 174 BC under the patronage of King Antiochus IV Epiphanes during Macedonian rule. However, after the death of Antiochus in 164 BC, work was again delayed. In 86 BC, during Roman rule, General Sulla brought two columns from the unfinished temple to Rome to decorate the temple of Capitoline Jupiter on the Capitoline Hill, influencing the development of the Corinthian style in Rome.

Emperor Hadrian took up the project again in the 2nd century, completing it in 129 (or 131 according to some sources). Although the exact date of its destruction is unknown, it probably occurred during the Middle Ages due to an earthquake, and its ruins were used as building material.

The temple, built in marble from Mount Pentelicus, was 96 meters long and 40 meters wide. It had 104 Corinthian columns, each 17 meters high and 2.6 meters in diameter. Only 16 of these columns survive today. Hadrian dedicated the temple to Zeus and placed an ivory statue of the god in its cella. Although the original sculptures have not survived, excavations were carried out in 1889-1896 and in the 1960s, revealing the ruins that today are a historic district managed by the Ephorate of Antiquities of the Greek Ministry of the Interior.