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.
The Goseck circle is a Neolithic circle structure. It may be the oldest and best known of the Circular Enclosures associated with the Central European Neolithic. It also may be one of the oldest Solar observatories in the world. It consists of a set of concentric ditches 75 metres across and two palisade rings containing gates in places aligned with sunrise and sunset on the solstice days.
Its construction is dated to c. 4900 BC, and it seems to have remained in use until 4600 BC. This corresponds to the transitional phase between the Neolithic Linear Pottery and Stroke-ornamented ware cultures. It is one of a larger group of so-called Circular Enclosures in the Elbe and Danube region, most of which show similar alignments.
Excavators also found the remains of what may have been ritual fires, animal and human bones, and a headless skeleton near the southeastern gate, that could be interpreted as traces of human sacrifice or specific burial ritual. There is no sign of fire or of other destruction, so why the site was abandoned is unknown. Later villagers built a defensive moat following the ditches of the old enclosure.
The Goseck ring is one of the best preserved and extensively investigated of the many similar structures built at around the same time. Traces of the original configuration reveal that the Goseck ring consisted of four concentric circles, a mound, a ditch, and two wooden palisades. The palisades had three sets of gates facing southeast, southwest, and north. At the winter solstice, observers at the center would have seen the sun rise and set through the southeast and southwest gates.
Archaeologists generally agree that Goseck circle was used for observation of the course of the Sun in the course of the solar year. Together with calendar calculations, it allowed coordinating an easily judged lunar calendar with the more demanding measurements of a solar calendar.