The Tabula Peutingeriana, the most ancient geographical map, mentions the settlement by the name of Sepomaia. In 876 it was attacked and destroyed by Prince Domagoj. The castle of Sipar was still inhabited in the years after 1552, when it was bought by the Rotas from Momjan. It previously belonged to the Bratti brothers from Koper, and before that to the bishop of Triest.
Little remains nowadays of the old buildings and the gate. The land extension stretching into the sea has become gradually thinned to its present state, due to slow seismic changes. The phenomenon is responsible for the fact that the western coast of Istria sinks about one millimetre a year, that is two metres in 2000 years. This stretch of coast has been a naturist resort for many years now.