Santa Marta was initially built in the late 15th-century but rebuilt at the end of the 16th century by the Confraternity of Santa Marta, a confraternity of disciplinanti (or flagellants). To the right of the entrance, they built an oratory.
Of the original decoration only one altar remains, and traces of frescoes in the presbytery and some lunettes in the walls of the oratory. Deconsecrated after World War Two, it became the property of the Commune of Ivrea in the 1970s, who converted it into a conference hall. The Baroque portal was moved to the parish church of San Bernardino in Ivrea.
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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.