A visit to Antakya (ahn-TAHK-yah, also called Hatay), three hours' ride southeast from Adana, is a detour from most travelers' routes, requiring a trip south over the Belen Pass (740 meters, 2428 feet) but it's definitely worth it.
If you're on your way to Syria, however, Antakya is right on your route, with easy transport to the border—though the Syrian civil war keeps most people from visiting that once-beautiful land.
Known as Antioch ad Orontes in Roman times, this is where St Peter is said to have preached in a cave belonging to St Luke. The cave, gouged from the side of Mt Sipylus (Spil Dağı) is thus said to be the first Christian church. You can visit it.
While you're in the area you might want to take a side trip to Samandağ (Seleucia ad Piera), 29 km (18 miles) SW on the Mediterranean (map), especially since Antakya is usually very hot and dry (see When to Go for more.)
By the way, the province of Hatay, of which Antakya is the capital, was part of Ottoman Syria and, after World War I, part of French Mandate Syria, but joined the Turkish Republic by plebiscite just before World War II. There's more about this in my humorous travel memoir, Turkey: Bright Sun, Strong Tea, in this excerpt.
—by Tom Brosnahan