Tsikhisdziri is home to an archaeological site and ruins of a Late Antique fortified town, which is identified with the Roman-built city-fortress of Petra.
Petra, founded at the behest of the emperor Justinian I in 535 and, after a series of battles for the possession of that city during the Lazic War with Sasanid Iran, was demolished by the Romans themselves to prevent it again becoming the enemy's target in 551. Later, the locale continued to be home to a stronghold of some importance.
The Tsikhisdziri fortress was situated on two coastal hills, connected to each other through double walls. On the territory of the citadel, the area of which totals around 1.5 h, are the ruins of a 6th-century three-nave basilica with the dimensions of 33X17.80 m, with narthex, projecting apse, and floor mosaic, and remains of two other churches, one from the early Christian period and the other dated to the High Middle Ages. Close to the basilica is a 6th-century bath and a water cistern. North to the citadel are the ruins of an urban settlement and hundreds of burials. These structures date from the Late Antiquity to the Middle Ages.
References:Celje Castle was once the largest fortification on Slovenian territory. The first fortified building on the site (a Romanesque palace) was built in the first half of the 13th century by the Counts of Heunburg from Carinthia on the stony outcrop on the western side of the ridge where the castle stands. It had five sides, or four plus the southern side, which was a natural defence. The first written records of the castle date back to between 1125 and 1137; it was probably built by Count Gunter. In the western section of the castle, there was a building with several floors. Remains of the walls of this palatium have survived. In the eastern section, there was an enclosed courtyard with large water reservoirs. The eastern wall, which protects the castle from its most exposed side, was around three metres thicker than the rest of the curtain wall. The wall was topped with a parapet and protected walkway.