Near the Tagliamento, on a rock spur, in one of the most picturesque and scenic spots of Ragogna, the remains of ancient Castle of Reunia (or St. Peter) are built, its construction dates back to the 11th century. Only recently, after many years of abandonment, it underwent a careful restructuring. From the road that climbs to the mountain you can see the remains of the main tower and the walls of the courtyard, the inner courtyard and the north door. Over the centuries, several noble families (Eppenstein, von Wallenstein and Porcia) lived in the Castle, which was damaged by an earthquake (1511) and a fire (1560). Abandoned by its owners, it was donated to the Ragogna Commune at the end of the 18th century. Along the access road there is a tombstone dedicated to Corporal Angelo Ruggeri, in the form of the IV Company of the 2nd Regiment Genio Zappatori, who died on 2 August 1909 during the fortification work of Monte di Ragogna. On 30 and 31 October 1917, the Castle was one of the brigade resistance stamps of Austro-Germanic.