Monnow Bridge in Monmouth is the only remaining fortified river bridge in Great Britain with its gate tower standing on the bridge. Such bridge towers were common across Europe from medieval times, but many were destroyed due to urban expansion.
According to the local tradition, construction of Monnow Bridge began in 1272 to replace a 12th-century Norman timber bridge. Through the medieval era, the English Civil War, and the Chartist uprising, the bridge played a significant, if ineffectual, role in defending Monmouth. It also served as a gaol, a munitions store, a lodge, an advertising hoarding, a focus for celebrations and, most significantly, as a toll gate. Much of the medieval development of Monmouth was funded by the taxes and tolls the borough was entitled to raise through royal charter. The tolls were collected through control of the points of entry to the town, including the gatehouse on Monnow Bridge.
Built predominantly of Old Red Sandstone, the bridge was the subject of significant reconstruction and rebuilding in the 18th and 19th centuries. In those centuries, it also became a popular subject for artists; Turner, Gastineau and Cotman produced sketches of the bridge and gate. In the 20th century, it suffered increasing damage as higher volumes of traffic and the use of ever-larger vehicles led to several serious accidents. In the 21st century, the construction of a new road crossing to the south enabled the pedestrianisation of the bridge.
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.