The Temple of Olympian Zeus is the largest temple in Greece, completed over a short 700 years from 590 BC to AD 131. Over the next 2,000 years, this is what remains of the original 104 columns. Just 15 remain standing, so you better book your flight to Greece in the next 500 years or you may not be able to see them! They are absolutely huge, incredible to think of the engineering of this ancient wonder. The original plans called for a temple twice its size, but it was abandon due to a lack of funds (not much has changed between then and now with funding issues!).