Jerinin Grad, Grabovac

The original fortification was built during the reign of Justinian I, the emperor of the Eastern Roman Empire, in the 6th century. The town flourished under administration of Princess Milica of Serbia. Its nickname however implicates that the latest fortification was built under the overwatch of Eirene Kantakouzene, the wife of Đurađ Branković, infamous in the folk for putting maximum work load onto the peasantry for building very demanding fortifications on steep mountain tops. There are several medieval towns in Serbia that are nicknamed as Eirene's Town.

Not much is known about Grabovac, however the latest findings imply that the fortified town was three times bigger than Koznik, and two times bigger than Maglič. It is estimated to include the surface of 1 hectare, and the fortification itself is located on the altitude of 300 meters. The fortification is accessible via a foot trail next to the Grahovac-Lozna road. Around 350 meters remain preserved, among which the tallest part is 8 meters tall and 2 meters thick. There are also remains of two towers that were connected to the main citadel by a long wall.