The Beul? gate, by which the Acropolis is accessed today, stands to the west of the Propylaia. It was built in the mid-third century AD as part of a program to protect the sacred precinct, possibly after the destructive invasion of the Herulians in 267 AD. Together with another gate located under the tower of Athena Nike, it was built into a strong fortification wall erected west of the Propylaia. The gate was named after the French archaeologist who investigated this area in 1852.
The gate is framed to the north and south by two rectangular towers. Both the gate and the towers are made of reused building material from earlier structures, such as the choregic monument of Nikias (late fourth century BC), which stood on the south slope of the Acropolis (only the monument's foundations are visible today between the theatre of Dionysus and the stoa of Eumenes). The votive inscription mentioning the choregic victory of Nikias Nikodemos is embedded in the wall above the gate's epistyle.
The monument is currently under conservation by the Department of Restoration of Ancient Monuments of the Ministry of Culture.