Lanzada is an archaeological site is composed of a castro (hillfort settlement), a necropolis, a medieval fortification and a chapel. A bronze socketed axe with two loops was found in the vicinity of the town of A Lanzada and is now housed in the National Archaeological Museum. Three more axes were uncovered in another part of the site, two of which belonged to the Marquis of Riestra and one that he gifted to an English subject. In the summer of 1969, a bronze Irish-style sickle was found among the remains of a landslide in the Norte del Castro area near the chapel.
Excavations revealed the existence of a castro settlement and a large late Roman necropolis with cremation and inhumation tombs. Bone and bronze pins, coins, shoe nails, and tegulae or flagstone graves were also recovered. The settlement and the necropolis are on both sides of the road. In 1969 and 1972 a stratigraphic analysis confirmed the existence of the settlement and its occupation from the late Bronze Era to the last stages of the Romanisation process, which makes it very significant.
Lastly, there is a Roman stela on the south side of a path known as A Ponte, which connects the mainland to the isle where the chapel is located. Fragments of castro pottery were found on the isle.
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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.