The fortifications at Castelmur may be, after the Three Castles of Bellinzona, the most important example of medieval valley fortifications in modern Switzerland.
The castle site has been occupied and fortified since at least the Roman era. The important trade road over the Septimer Pass runs through the Val Bregaglia. The Romans built a guard station and village named 'Murus' according to the 3rd century Itinerarium Antonini. The foundations of several buildings as well as one building's hypocaust and two small votive altars have been excavated from the Roman settlement.
After the fall of the Western Roman Empire the Castelmur next appears in 842 as castellum ad Bergalliam. At that time it was owned by the Emperor and held by Constantius of Sargans. In 960 Emperor Otto I granted the castle and right to collect tolls to the Bishop of Chur to help secure this important alpine trade route. In 988 Emperor Otto IIIconfirmed his grandfather's grant to the Bishop and specifically mentioned both the castle and the nearby Nossa Donna Church. The current tower was probably built around 1200.
Over the following centuries the Bishop of Chur and the town of Chiavenna quarreled over Castelmur and in 1121 or 1122 the town captured the castle. However, Pope Callixtus II intervened and forced Chiavenna to return the castle to Chur. In 1190 the Bishop granted the castle to Albertus de Castello Muro or Castelmur. His descendants ruled over the castle until 1264 when Albertus Popus Castelmur stole cattle from the nobles of Chiavenna and Piuro, led to an invasion and the castle being conquered in 1268. These nobles held the Castelmur for four years before returning it to the Castelmurs in 1272. Around 1340 the Bishop reclaimed the castle and then mortgaged it to the Planta family for 200 Marks. To discourage the Planta family from trying to completely annex the lucrative castle and tolls, in 1410 the Bishop mortgaged it to Jacob Perutt von Castelmur for 150 Gulden. Twenty years later the Bishop used a loan from the Salis family to buy out the mortgage and give it to them. In 1490, for the last time, the Bishop gave the castle to Michel Pfannholz. However, he abandoned it in 1538 and left the castle to fall into ruin.
The castle ruins were repaired and cleaned in the 19th century by Baron Giovanni de Castelmur. In addition to the castle, he repaired and rededicated the nearby church of S. Maria (Nossa Donna). The church's bell tower is a Romanesque construction, but much of the church itself, including the nave are from this 19th century renovation. The church was first mentioned in 988.
The original fortification was a wall or letzi that straddled the valley between the Maira river and the castle hill. This wall, which was up to 3.7 meters thick, had a gate that could be blocked by logs if needed. The remains of this wall are north-west of the main tower. In the 12th century a square tower with a ring wall were built on top of the steep outcrop. This tower allowed a noble family to take up residence and changed Castelmur from a toll collecting station into a regional administrative center. The five story square tower was 12 m on a side with 2.4 m walls on the lowest story. Much of this tower is still visible. The castle church was built below the castle hill south of the main tower. At some point, a second tower was added on a tall hill south of the main tower. This building measured about 10 m × 10 m, though very little of it still remain.References:
The Broch of Gurness is an Iron Age broch village. Settlement here began sometime between 500 and 200 BC. At the centre of the settlement is a stone tower or broch, which once probably reached a height of around 10 metres. Its interior is divided into sections by upright slabs. The tower features two skins of drystone walls, with stone-floored galleries in between. These are accessed by steps. Stone ledges suggest that there was once an upper storey with a timber floor. The roof would have been thatched, surrounded by a wall walk linked by stairs to the ground floor. The broch features two hearths and a subterranean stone cistern with steps leading down into it. It is thought to have some religious significance, relating to an Iron Age cult of the underground.
The remains of the central tower are up to 3.6 metres high, and the stone walls are up to 4.1 metres thick. The tower was likely inhabited by the principal family or clan of the area but also served as a last resort for the village in case of an attack.
The broch continued to be inhabited while it began to collapse and the original structures were altered. The cistern was filled in and the interior was repartitioned. The ruin visible today reflects this secondary phase of the broch's use.
The site is surrounded by three ditches cut out of the rock with stone ramparts, encircling an area of around 45 metres diameter. The remains of numerous small stone dwellings with small yards and sheds can be found between the inner ditch and the tower. These were built after the tower, but were a part of the settlement's initial conception. A 'main street' connects the outer entrance to the broch. The settlement is the best-preserved of all broch villages.
Pieces of a Roman amphora dating to before 60 AD were found here, lending weight to the record that a 'King of Orkney' submitted to Emperor Claudius at Colchester in 43 AD.
At some point after 100 AD the broch was abandoned and the ditches filled in. It is thought that settlement at the broch continued into the 5th century AD, the period known as Pictish times. By that time the broch was not used anymore and some of its stones were reused to build smaller dwellings on top of the earlier buildings. Until about the 8th century, the site was just a single farmstead.
In the 9th century, a Norse woman was buried at the site in a stone-lined grave with two bronze brooches and a sickle and knife made from iron. Other finds suggest that Norse men were buried here too.