The Propylaea is the monumental gateway to the Acropolis.
Accessed by gigantic meandering stone steps, most of the original structure no longer exists.
The Propylea was designed by the architect Mnesikles and constructed in 437-432 B.C.
Originally, the structure included a central building and two lateral wings.
Presently the Propylea is mostly open to the sky and has only the remains of monumental columns seen in this image.