Guercino’s painting, “The Flaying of Marsyas by Apollo” (1618-1622), depicts the cruel fate suffered by the Arcadian god Marsyas when he challenged Apollo in a musical competition, and lost.
Marsyas was skinned alive in a cave near Celaenae, Turkey for his hubris to challenge a god. Apollo then nailed Marsyas' skin to a pine tree, near Lake Aulocrene (the Turkish Karakuyu Gölü).
The Greek god Pan is the other name of Marsyas. Remember that there are two stone heads in the Shugborough relief sculpture, one of which bears a strong likeness to the goat-horned Pan. This confirms my claim that there is a connection between Guercino’s painting and that of Poussin’s.
Using the two intersecting lines obtained by connecting the Madara Rider with the Hagia Sophia, and Atlantis with the Hagia Sophia as my image, I projected its horizontally reversed image using the line connecting Atlantis and the Hagia Sophia as my vertical axis. The result gave me the position of where the cave of Marsyas ought to be (38.882°N, 30.994°E), and these coordinates point to the Northern border of Bolvadin, Turkey.
Keep in mind that our original image is not perfectly perpendicular, having an excess of 2.4° from the ideal 90° angle between the intersecting lines. This error will cause some minor displacement of where the cave of Marsyas ought to be located.
There is a city named Apamea (38° 4′ 18″ N, 30° 9′ 56″ E) which is partly occupied by Dinar and where according to Strabo the source of the Marsyas river lies.
According to Xenophon, the source of the Marsyas River is near a cave where Apollo flayed Marsyas and where his skin was hung:
"The great king also has a palace in Celaenae, a strong place, on the sources of another river, the Marsyas, at the foot of the acropolis. This river also flows through the city, discharging itself into the Maeander, and is five-and-twenty feet broad. Here is the place where Apollo is said to have flayed Marsyas, when he had conquered him in the contest of skill. He hung up the skin of the conquered man, in the cavern where the spring wells forth and hence the name of the river, Marsyas." Xenophon Anabasis
This cave according to another legend is near Lake Aulocrene, or the Turkish Karakuyu Gölü (38° 4′ 30”N, 30° 16′ 27”E).
Marsyas was skinned alive in a cave near Celaenae, Turkey for his 
