The sanctuary encompassed a trapezoidal courtyard enclosed by walls. Within this space, there stood the altar of Zeus Herkeios, the guardian of the hearth and the courtyard, positioned beneath the sacred Olive Tree that Athena herself had planted. Towards the west, an entrance stoa connected it to the Propylea. In the northeast corner, an intricate entrance led to the north porch and the entire Etrechtheion complex. Towards the east, a small opening allowed a glimpse of the Thalassa of Poseidon.

Access to what some believed to be the tomb of Cecrops was granted through the southeast corner. Within the sanctuary, the revered olive tree, bestowed by Athena as a gift to the city of Athens following her triumph over Poseidon in the competition for the land of Attica, was also located.

The Pandroseion underwent alterations when the Erechtheion was built attached to its eastern end (circa 431-406 BCE or 421-406 BCE). Then, the entrance was through a small undecorated door at the right of the elaborate entrance at the north porch of the Erechtheum, while the two sancturies were also directly connected with a small door in the western wall of the Erechtheion. At that time, the court of the sanctuary was paved and part of Kekrops' tomb was integrated under the porch of the Caryatids.

circa 421 BCE

Architectural Description
The Pandroseion (illustration) was founded in the area of the Acropolis where the oldest sacred spots of the Athenian mythology were located, such as the signs of the contest between Athena and Poseidon for the patronage of the city; the sacred olive tree, which according to the legend sprung when the goddess struck the rock with her spear, giving her the victory; the salty spring, which appeared when Poseidon struck his trident; and the tomb of king Kekrops (inspect), who was the judge or a witness of the contest of the two gods, according to the myth.

circa 421 BCE

Today, the remains of this structure are quite scant. Very few stones of this classical sanctuary are preserved at the west wall of the Erechtheum, as well as parts of the foundation of its north boundary. These remains indicate that it was an open-air sanctuary of a trapezoidal plan with a stoa of the Ionic order at the north-side. The entrance (inspect) of the sanctuary was a small propylon (gate) at the eastern end of the stoa. The altar of Herkeios Zeus, protector of the family, was located in the court under the sacred olive tree.

circa 421 BCE

Sacred Olive Tree
The sacred olive tree of Athena was enclosed in the sanctuary of Pandrosos, while Kekrops' tomb was protected by a separate precinct wall at the south-east. The early Pandroseion, whose form is unknown, was destroyed by the Persians in 480 BCE.

The olive tree that exists in the sanctuary today was planted in the beginning of the twentieth century CE in memory of Athena's sacred tree.