Hadrian built this massive temple -- or rather, finished the construction that began in the 6th century B.C. and continued on and off (more off than on) for 700 years. At 108m long and 43m wide (360*143 ft.), the Olympieion, also known as the Kolonnes (Columns), was one of the largest temples in the ancient world. The 17m-high (56-ft.) Pentelic marble columns that remain standing, as well as the one sprawled on the ground, give a good idea of how impressive this forest of columns must have been -- although it may be more appealing as a ruin than it ever was as a contender for the title "mother of all temples." Inside, side by side, were once statues of Zeus and of Hadrian.