The Archbishops of Mainz had the Mildenburg castle built at the end of the 12th century to secure their powerful position and to serve as a customs office. Around 1200, the castle keep was added, the first official reference dates to 1226. Rather diverse periods in history affected the castle: extending, capturing, damaging and reconstructing.
Mildenburg the seat of the Oberamtmann, the Archbishop's local administrator until 1803. It then passed to the Princes of Leiningen before Carl Gottlieb Horstig purchased it in 1825. It now houses a museum of icons and contemporary art. The castle’s inner ward once held the Teutonenstein, a 5 m-tall sandstone column found on Greinberg, the inscription of which is still a puzzle to this day.
Narikala is an ancient fortress overlooking Tbilisi, the capital of Georgia, and the Kura River. The fortress consists of two walled sections on a steep hill between the sulphur baths and the botanical gardens of Tbilisi. On the lower court there is the recently restored St Nicholas church. Newly built in 1996–1997, it replaces the original 13th-century church that was destroyed in a fire. The new church is of 'prescribed cross' type, having doors on three sides. The internal part of the church is decorated with the frescos showing scenes both from the Bible and history of Georgia.
The fortress was established in the 4th century and it was a Persian citadel. It was considerably expanded by the Umayyads in the 7th century and later, by king David the Builder (1089–1125). Most of extant fortifications date from the 16th and 17th centuries. In 1827, parts of the fortress were damaged by an earthquake and demolished.