The regional center of Develi 45km/28mi south of Kayseri at the foot of the Erciyes Dagi was formed from an amalgamation of three communities in the 19th century: Everek (Christian population, bazaar and administrative center), Agostan and Fenisse. The old town of Yukari Develi lies to the south on the hillside. The medieval castle ruins of
Develi Kalesi overlooks the Armenian quarter of the town from a rocky outcrop. Some of the town's interesting sights include the late 13th century Ulu Cami (Develi Cami, Sivasi Hatun Camii, Seljuk graves in the cemetery), the Seyit Serif Türbesi (1276) and the ruins of the Church of St Kosmas and Damian in the old Christian quarter.
The peaks of the Erciyes Dagi, Ala Dagi and Tahtali Daglari remain covered in snow until late spring and form both a picturesque backdrop to the Sultan's Marshes and a birds' paradise with reeded shallows and floating reed islands. When an Ice Age lake dried up near the marshlands mud-flats formed which, as a consequence of artificial drainage, often dried out completely in the summer months, thus restricting the habitats of much wetland wild-life. A number of initiatives have persuaded the authorities to turn the Sultan's Marshes to the southwest into a nature reserve. The local inhabitants use the reeds as roof thatch and for the manufacture of matting.