More than 400 round stone structures crowd the interior of the citadel — the signature architectural style of the Chachapoyas. Unlike the rectangular buildings of the Inca, these circular towers were used as homes, storage, and possibly ceremonial spaces. Many are decorated with geometric friezes: diamond patterns, serpentine bands, and stylised figures worked into the stone. A number have been restored, giving a clearer picture of how the city looked at its peak.