Varbola linnus

The Varbola Stronghold (Latin: Castrum Warbole, Estonian: Varbola Jaanilinn) was the largest circular rampart fortress and trading centre built in Estonia, in Harju County (Latin: Harria) in the 10th – 12th centuries. Parts of the ruins of the 580-metre (1,900 ft) long and 8-to-10-metre (26 to 33 ft) high limestone wall of the fortress stand to this day. The long gateways with multiple gates were built to defend the entrances. In these sections higher defensive towers were erected.