Otepää castle hill is the site of an ancient stronghold. It is speculated that a fortified settlement may have existed there even before Christ. The first major extension works were initiated in the 11th and 12th century when the castle was at the crossroads of important trading routes. Herman I, the bishop of Tartu, established there the first stronghold of its diocese. A settlement, which was mainly populated by craftsmen and merchants, appeared around the bishop’s castle in the 13th century. The castle was the first known brick building in Estonia.
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.