In the middle of the vertical carved rock above the Theatre of Dionysos, is the cave of the choregic monument of Thrasyllos. Pausanias refers to it indirectly, informing us that a representation of Apollo and Artemis slaughtering the children of Niobe decorated its interior.

The choregic monument of Thrasyllos consisted of a marble facade in front of the natural cave. Ιts facade consisted of two door openings, with antae and a central pillar, a Doric architrave with continuous guttae, an ionic frieze and a cornice which supported the bases for the choregic tripods. The frieze is decorated with a single wreath of ivy leaves in the middle, trophy for the winner of the theatre competitions, and ten more olive wreaths.

According to the inscription on the architrave, the monument was built by the sponsor Thrasyllos during the archonship of Neaichmos (320/319 BC). The next historical phase, documented again by the surviving choregic inscriptions, includes the modification of the monument's upper section and the positioning of two additional tripods by the son of Thrasyllos, Thrasykles, victorious sponsor of the theatre competition during the time of Pytharatos' archonship (271/270 BC). The religious use of the monument during the Early-Christian times is doubtless.

Testimony from 17th century foreign travelers, confirms the existence of a two-part Christian chapel. This was dedicated to ?Virgin Mary of the Rocks?. Remains of this period can still be seen in the interior of the cave. The condition of the monument during the Ottoman Occupation was displayed in 18th and early 19th century pictorial material. As all these drawings testify, a statue of Dionysos replaced the central tripod of Thrasyllos. This intervention perhaps dates back in the Roman times. The statue was violently removed in 1802 on behalf of Lord Elgin and is now exhibited in the British Museum.

The Thrasyllos monument, which for over 2000 years had remained almost intact, was finally destroyed in 1827, during the siege of the Acropolis by the Turks.

In the middle of the 19th century, while the Archaeological Society had scheduled the restoration of the monument, part of its architectural material was recarved and reused during the repair work of the Byzantine church of Soteira Lykodemou, now chiefly known as the Russian Church. The meticulous drawings by J. Stuart and N. Revett carried out during their visit in Athens in 1751-3, document the accurate form and dimensions of the ancient monument and along with new measurements of the surviving parts, formed the basis for the restoration project of the monument initiated in 2002.