<Location> Kerameikos Site, Athens, Attica, Greece
The photo left is how are positioned the Pompeion and the Propylon.
The Pompeion is a public building situated within the city-wall of Themistokles, between the Sacred and the Dipylon Gates. It was the place where the Panathenaic procession (= "pompe" in Ancient Greek) got prepared and started toward Eleusis. The equipments for the procession were stored here, when they were not used.
It was first constructed in the fourth century BCE (Classical period). The building was made of a monumental entrance (propylon), a spacious peristyle court, and several rooms. The eminent citizens and privilaged people had ritual dinner of the Panathenaic Festival here. In the courtyard there used to be statues and paintings, and the dining rooms were decorated with mosaics.
As Athens supported the king of Pontos during the Mithridaic War, it was sacked by the Roman general Sulla in 86 BCE as punishment. The Roman army under Sulla entered Athens breaking the wall in this area and destoyed buildings here, including the Pompeion. The destruction and massacre were remembered by Plutarch. The Pompeion was destroyed at this occation.
After long abandonment, it was rebuilt in the second century CE (maybe under the reign of Antoninus Pius). This is the most visible phase of the building now.
This restored building was again devastated by the Heruli in 267, but again rebuilt in the fourth century. According to Mee and Spawforth, the second century building was a basilica, and the fouth century one were two stoas.