The central tower and oldest part of the Rietberg Castle was built in the 13th century, though it may have been built around an earlier 12th-century tower. It was built for the Lords of Rietberg, who in 1286 were vassals of the Freiherr von Sax-Misox. In the 14th century they became vassals of the Bishop of Chur. At that time they held the castle and estates in Schams, Chur and Oberhalbstein and were the bishop's representative in Oberhalbstein and Oberengadin. The last male member of the Rietberg line, Johann von Reitberg, attempted to guarantee that the castle and his estates would pass to his wife, Berta von Rhäzüns, and to his relative Hermann von Landenberg. However, after his death in 1349 the Bishop of Chur claimed the castle. In 1353 he succeed in forcing the Landenbergs to sign away their claim to the castle and estates. Other claims to the castle continued to simmer until 1388 then the Bishop paid off the Lords of Rhäzüns and Lumerins to settle their claims.
The Bishop used the castle, its estates and the office of vogt as collateral for loans from a number of wealthy families or as a reward for gifts from those same families. In 1384 Eglolf von Juvalt lived in the castle. In 1398 the bishop mortgaged the castle to Jakob von Castelmur for 500 silver marks. It was mortgaged again in 1409 to Conradin Rambach and the cathedral chapter, again in 1426 to Bartolomäus Planta and in 1447 to Hans Wellenberg. In 1450 it was mortgaged to Hans Ringg, who passed it to his son Wilhelm in 1483. It continued to used as collateral into the 16th and 17th centuries. Around 1530 it went to Anton von Travers, followed by Hercules von Salis in 1554. In 1617 it came to the Planta family.
It was the site of the murder of Pompeius Planta in 1621 by Jörg Jenatsch during the conflicts between Catholics and Protestants known as the Bündner Wirren.References:
The Arch of Constantine is situated between the Colosseum and the Palatine Hill. It was erected by the Roman Senate to commemorate Constantine I's victory over Maxentius at the Battle of Milvian Bridge in 312. Dedicated in 315, it is the largest Roman triumphal arch. The arch spans the Via triumphalis, the way taken by the emperors when they entered the city in triumph.
Though dedicated to Constantine, much of the decorative material incorporated earlier work from the time of the emperors Trajan (98-117), Hadrian (117-138) and Marcus Aurelius (161-180), and is thus a collage. The last of the existing triumphal arches in Rome, it is also the only one to make extensive use of spolia, reusing several major reliefs from 2nd century imperial monuments, which give a striking and famous stylistic contrast to the sculpture newly created for the arch.
The arch is 21 m high, 25.9 m wide and 7.4 m deep. Above the archways is placed the attic, composed of brickwork reveted (faced) with marble. A staircase within the arch is entered from a door at some height from the ground, on the west side, facing the Palatine Hill. The general design with a main part structured by detached columns and an attic with the main inscription above is modelled after the example of the Arch of Septimius Severus on the Roman Forum.