The Castle Hill of Grosio is dominated by two castles. The Old Castle (Castello Vecchio) was probably built at the end of the 10th century. The Castello Nuovo was built as a stronghold between 1350 and 1375 due to the military-strategic needs of the 14th century.
The castle is surrounded by a double defense wall and had next to e solid keep even a fortified internal tower. Apart from a military expedition by Giovanni Cane in 1376 to Bormio, which had its starting point here, the Castello Nuovo was never involved in military confrontation or siege. Today the castle is only preserved as a castle ruin because after 1526 the new political power in Valtellina ordered the destruction of all fortifications in the valley. That way the dominion of the Three Leagues wanted to avoid any potential danger that could emanate from their own castles.
During the period of the Bündner Wirren (1620-1639), the Thirty Years' War in Europe, the structure was used by the French under Duke Rohan as a military base and got partially restored. The Castello Nuovo is nowadays the best-preserved example of all the historic defensive structures in the Valtellina.
Between 1992 and 1997 in the area of the Castello Nuovo archaeological excavations could document the remains of a bronze and iron age settlement, dating from the middle of the 2nd to the end of the 1st millennium BC. Some of the small finds are now exposed in the excavation museum.
References:The Broch of Clickimin is a large and well preserved, though somewhat restored broch near Lerwick. Originally built on an island in Clickimin Loch (now increased in size by silting and drainage), it was approached by a stone causeway. The water-level in the loch was reduced in 1874, leaving the broch high and dry. The broch is situated within a walled enclosure and, unusually for brochs, features a large 'blockhouse' between the opening in the enclosure and the broch itself. Another unusual feature is a stone slab featuring sculptured footprints, located in the causeway which approached the site. Situated across the loch is the Clickimin Leisure Centre.