<Location> Near the Theatre of Dionysos, Athens, Attica, Greece
The two columns in the photo above are a choregic monument, installed up on the akropolis hill, just above the theatre of Dionysos. If we see at a litte more distance, it looks as in the photo right.
In front of the cave below the columns, there used to be a choregic monument of Thrasyllos (321/20 BC) and his son Thrasykles (270 BC), as it is known from inscriptions. The cave was dedicated to Dionysos by Thrasyllos. In the Christian period, it was turned into a chapel called the Panagia Spiliotissa (Madonna in the Cave). The monument itself was destroyed in 1827 by the Turks during the siege.
The columns looks as in the photo left, when seen from the Acropolis. The two Corinthian columns were dated to the 4th century BC, but the relation to the Thrasyllos' monument is unclear.
As I have already explained elsewhere, choregos was a patron of theatrical play at theatrical contest. If his play won, the patron got a bronze tripod as prize. The successful choregoi built various monuments, and put their tripod on them to commemorate their victory. The most famous example is the Monument of Lysikrates in Plaka, but there are also elsewhere, like one in the Athenian Agora.
In the photo below is the Choregic Monument of Nikias (320/319 BC), situated to the west of the Theatre. It looked like a Doric temple, but now only its foundation remains. The materials of the monument were reused to construct the Beulé Gate of the Acropolis in the third century AD. The inscription is still visible.