In the cove Sepen, just a few kilometres by air to the south of Omišalj, there is an inexhaustible site of archaeological heritage. The first traces of settling in the area date back into the 1st century when the Roman town Fulfinum emerged. Its emergence is related to the construction of the city for the retired Roman soldiers during the Flavian dynasty. A good geographical position caused the development of seafaring and trade. The past archaeological research discovered the city forum, the heart of every city from the Roman age, the centre of the social and religious life of the Romans. Here, only fifty meters from the sea, is where the foundations of the temple, the civilian basilica and the commercial edifices (tabernae) were found. In one moment during the 3rd century, the city simply died out, at least when it comes to its original monumental form. Still, life continued. Traces of more modest settlement of the area were found, probably connected with the port which is still in function.
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.