The Temple of Olympian Zeus, also known as the Olympieion or Columns of the Olympian Zeus, is a former colossal temple at the centre of the Greek capital, Athens. It was dedicated to "Olympian" Zeus, a name originating from his position as head of the Olympian gods. Construction began in the 6th century BC during the rule of the Athenian tyrants, who envisaged building the greatest temple in the ancient world, but it was not completed until the reign of Roman Emperor Hadrian in the 2nd century AD, some 638 years after the project had begun. During the Roman period, the temple, which included 104 colossal columns, was renowned as the largest temple in Greece and housed one of the largest cult statues in the ancient world.

Athens is the capital and largest city of Greece. A major coastal urban area in the Mediterranean, Athens is also the capital of the Attica region and is the southernmost capital on the European mainland. With its urban area's population numbering over three million, it is the eighth largest urban area in the European Union. The Municipality of Athens, which constitutes a small administrative unit of the entire urban area, had a population of 643,452 (2021) within its official limits, and a land area of 38.96 km2 (15.04 sq mi).