The Acropolis restoration  is probably one of the longest running projects of its kind – The current programme of works started thirty five years ago. The completion of the works to the Propylaia – the gateway to the site marks a major milestone in the completion of these works.
Athens News Agency 
Restoration of Acropolis Propylaea completed
All scaffolding and cranes were fully removed from the Propylaea of the Acropolis, the monumental entrance, or gateway, to the Acropolis, following completion of the restoration work on the central building of the structure.
The Propylaea was built under the direction of Athenian leader Pericles, but the building itself was designed by the architect Mnesicles, while construction began in 437 BCE and was terminated in 432 BCE, while the building was still unfinished.
The Propylaea is constructed of white Pentelic marble and gray Eleusian marble or limestone, used for accentuation.
The structure comprises a central building and two adjoining wings on the west, or outer, side and on the south side.
The core of the structure is the central building built with a standard six-column Doric facade on the west of the entrance to the Acropolis, and reflects the proportions, although not the size, of the columns of the Parthenon.
The central building contains the gate wall, about two-thirds of the way through it, while there are five gates in the wall: one for the central passageway, which was not paved and lay along the natural level of the ground, and two on either side at the level of the building’s eastern porch, five steps up from the level of the western porch. The central passageway was the culmination of the Sacred Way, which led to the Acropolis from Eleusis.