The archaeological park is one of the most beautiful places in the city and along the coast of Posillipo. Among the most important sites are the Seiano cave, the underwater park of Gaiola, the imperial villa of Pausilypon, the Odeon, the theatre and the Palace of the Spirits.
The ruins of the Roman villa of Vedius Pollio, also known as the Imperial Villa, include a 2000-seat theatre on the rocky promontary at the end of the Bay of Naples. Some of the villa's rooms can be seen with traces of the wall decorations while its marine structures and fish ponds are now part of the neighbouring submerged Gaiola Park. The villa was built in the first century BC by Publius Vedius Pollio. On his death in 15 BC, the villa was bequeathed to Augustus, and remained in imperial possession for his successors at least until Hadrian, as witnessed by a stamped water pipe. In various points the presence of water supply pipes (coated with hydraulic mortar) show the opulence of the facilities. Augustus demolished at least part of the house and constructed in its place a colonnade in honour of his wife Livia, which he dedicated in 7 BC.
The Palace of the Spirits is an archaeological complex on the coast near Marechiaro and was the nympheum of the villa and also built in the first century BC. The submerged parts of the ruins of the imperial villa and the rich and diverse marine and coastal natural environment can be seen via boat excursions.
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.