Cromwell's Castle is an artillery fort overlooking New Grimsby harbour on the island of Tresco in the Isles of Scilly. It comprises a tall, circular gun tower and an adjacent gun platform, and was designed to prevent enemy naval vessels from entering the harbour. The castle was built in two phases; Sir Robert Blake constructed the tower between 1651 and 1652 in the aftermath of the Parliamentary invasion of the islands at the end of the English Civil War, and Master Gunner Abraham Tovey added the gun platform during the War of Jenkins' Ear around 1739. The tower fell into disuse soon afterwards, and in the 21st century is managed by English Heritage and open to visitors.
References:Sigmaringen Castle was first mentioned in the year 1077 in the chronicles of Petershausen monastery. The oldest parts of the castle are concealed beneath the alterations made during the 17th and the 19th centuries. The secret of the earliest settlement built on this defendable rock will never be fully revealed: large-scale excavation work would be necessary, which the extensive land development renders impossible. Judging from the many Roman remains unearthed in the area around Sigmaringen, the 12th century keep known as the 'Roman Tower' could be traced back to a Roman predecessor.
The castle remains that have been preserved (gate, great hall and keep) date back to the Staufer period around 1200. The castle remains were integrated into subsequent buildings. The foundations of the castle buildings are to a large extent identical to the surrounding castle wall.
These remains give us a good idea of how the castle might have looked during the 12th century.