Starosel is a village in central Bulgaria, situated near the popular Spa resort of Hissar, Plovdiv Province. It lies at the foot of the Sredna Gora mountain range and the Pyasachnik River crosses it.
Starosel is mainly known for its abundance of ancient Neolithic and Thracian sites, with finds dating as far back as the 5-6 millennium BC. The village was in Antiquity an important and wealthy Thracian city in the 5th century BC, as evidenced by the excavations in the 20th century. Some of the sites include a large temple with a mausoleum in the Chetinyova Mogila tumulus; the Horizont tumulus, where the only known Thracian temple featuring a colonnade (a Doric one) is located, as well as 9 other tumuli in the surrounding area.