Mark 21 nuclear bomb
The Mark 21 nuclear bomb was a United States nuclear gravity bomb first produced in 1955. It was based on the TX-21 "Shrimp" prototype that had been detonated during the Castle Bravo test in March 1954. While most of the Operation Castle tests were intended to evaluate weapons intended for immediate stockpile, or which were already available for use as part of the Emergency Capability Program, Castle Bravo was intended to test a design which would drastically reduce the size and costs of the first generation of air-droppable atomic weapons (the Mk 14, Mk 17 & Mk 24). At long, in diameter, and weighing , the Mk-21 was half the length and one-third the weight of the Mk-17/24 weapons it replaced. Its minimum yield was specified at four megatons.
Castelmur Castle (Bondo)
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. It included the "porta bergalliae" a customs and toll station located nearby. 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 III confirmed 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.