The Varbola Stronghold was the largest circular rampart fortress and trading centre in Estonia in the 10th-12th centuries. The first record of Varbola is written by Henry of Livonia, who mentions the Castrum Warbole being besieged in 1211 for several days by Mstislav the Bold of Novgorod. The conflict was resolved with a payment of seven hundred Marks.
During the Livonian crusade Livonian Brothers of the Sword invaded the territory and the people from Varbola asked for the terms of peace. The terms offered by Livonian Brothers of the Sword were accepted by Varbolians, but later the people of Varbola became the subjects of the King of Denmark. On the basis of the Danish Census Book the estate surrounding the Varbola trading center remained a possession of the Lode family, nobility of Estonian origin at the time. The Varbola stronghold lost its importance only in the second quarter of the 14th century, after having played in important part in the anti-Christian and anti-German St. George's Night Uprising of 1343.
In the 16-17th centuries the stronghold was used as a cemetery. The first known fort plan dates from 1786 and was drawn by Ludwig August von Mellin. Archaeological excavations at the site have been undertaken in 1938-41, 1953 and 1974. Among the archaeological finds were dice made of bone.
Parts of the ruins of the 580 metre long and 8-10 metre high limestone wall of the fortress stand still this day. The long gateways with multiple gates were built to defend the entrances. In these sections higher defensive towers were erected. There was a 13 metre deep well in the middle of the fortress and the territory held about 90 structures with furnaces for accommodation built with limestone floors and foundations.
Derbent is the southernmost city in Russia, occupying the narrow gateway between the Caspian Sea and the Caucasus Mountains connecting the Eurasian steppes to the north and the Iranian Plateau to the south. Derbent claims to be the oldest city in Russia with historical documentation dating to the 8th century BCE. Due to its strategic location, over the course of history, the city changed ownership many times, particularly among the Persian, Arab, Mongol, Timurid, Shirvan and Iranian kingdoms.
Derbent has archaeological structures over 5,000 years old. As a result of this geographic peculiarity, the city developed between two walls, stretching from the mountains to the sea. These fortifications were continuously employed for a millennium and a half, longer than any other extant fortress in the world.
A traditionally and historically Iranian city, the first intensive settlement in the Derbent area dates from the 8th century BC. The site was intermittently controlled by the Persian monarchs, starting from the 6th century BC. Until the 4th century AD, it was part of Caucasian Albania which was a satrap of the Achaemenid Persian Empire. In the 5th century Derbent functioned as a border fortress and the seat of Sassanid Persians. Because of its strategic position on the northern branch of the Silk Route, the fortress was contested by the Khazars in the course of the Khazar-Arab Wars. In 654, Derbent was captured by the Arabs.
The Sassanid fortress does not exist any more, as the famous Derbent fortress as it stands today was built from the 12th century onward. Derbent became a strong military outpost and harbour of the Sassanid empire. During the 5th and 6th centuries, Derbent also became an important center for spreading the Christian faith in the Caucasus.
The site continued to be of great strategic importance until the 19th century. Today the fortifications consist of two parallel defence walls and Naryn-Kala Citadel. The walls are 3.6km long, stretching from the sea up to the mountains. They were built from stone and had 73 defence towers. 9 out of the 14 original gates remain.
In Naryn-Kala Citadel most of the old buildings, including a palace and a church, are now in ruins. It also holds baths and one of the oldest mosques in the former USSR.
In 2003, UNESCO included the old part of Derbent with traditional buildings in the World Heritage List.