Work starts on the Propylaia, the monumental western gateway to the Acropolis, designed by the architect Mnesikles as part of the Periklean rebuilding of the sanctuary after the Persian Wars.
Construction is suspended as the Peloponnesian War begins; the Propylaia remains unfinished, shaping the monument’s final, truncated form.
The traveler Pausanias describes paintings displayed in the Propylaia’s north wing (later called the Pinakotheke), providing key ancient testimony for how parts of the complex were used and experienced.
A fortified gateway (the Beulé Gate) is constructed as part of late-Roman defensive works associated with the post-Herulian rebuilding of Athens’ defenses, marking a shift toward viewing the Acropolis as a strategic strongpoint.
In the Middle Byzantine period, the Propylaia’s central section is converted to a church dedicated to the Taxiarches, reflecting the broader Christian re-use of major classical monuments.
Under the Florentine dukes, the Propylaia is turned into a ducal mansion/fortified residence, illustrating the monument’s continued strategic and administrative role in late medieval Athens.
A tall medieval tower (the Frankish Tower) is built on the Acropolis near the Propylaia, probably within the period of Frankish rule (the precise date is uncertain, but generally placed between the early 13th and mid-15th centuries).
During the Venetian siege of the Acropolis, a cannonball triggers an explosion in an Ottoman powder magazine located in the Propylaia, causing significant damage to the monument.
After the Ottoman garrison surrenders (March 1833), Greek authorities begin clearing post-classical additions; early works include demolitions in parts of the Propylaia complex as the Acropolis is redefined as an archaeological site.
French archaeologist Charles Ernest Beulé excavates and brings to light the Beulé Gate (1852–1853), permanently reshaping access and scholarly understanding of the Acropolis approach to the Propylaia.
The Frankish Tower—long integrated into the western Acropolis complex near the Propylaia—is demolished as part of efforts to remove later additions and foreground the classical monuments.
Engineer Nikolaos Balanos undertakes early 20th-century restorations on Acropolis monuments, including work on the Propylaia; later conservation assessment finds that iron reinforcements used in this period contributed to marble cracking and other damage as corrosion progressed.
Greece establishes the Committee for the Conservation of the Acropolis Monuments (ESMA), marking the start of a long-term, research-driven restoration framework that later guides major Propylaia interventions.
A full-scale restoration campaign proceeds to reverse earlier incompatible interventions and address pollution-related decay; milestones include dismantling and re-restoring elements (e.g., the central building’s coffered ceilings) and reassembling members with improved materials and documentation.
A major project begins to restore the superstructure of the central building, including dismantling remaining Balanos-restored members and reassembling with updated structural studies and conservation practice.
A focused program restores the southwest wing, repositioning numerous original architectural members, correcting earlier misplacements, and adding limited new pieces where required for stability and legibility of the monument.
Propylaia, Athenian Acropolis (437–432 BCE and later phases)
