The burial mound known as “Helvecia” near Shipka, Bulgaria, dates back to the mid-4th century BC. The entrance corridor of the Thracian tomb is constructed with stone walls. Beyond this corridor lies an antechamber, leading to a rectangular chamber distinguished by its distinctive covered ceiling. The ceiling, curved by the walls of both rooms, is intersected by a horizontal zone, signifying the shift from the double-pitched to the semi-cylindrical design characteristic of Thracian architecture.