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.
Castello Brown
The castle's site is well suited for harbour defence, and appears to have been so used since the 15th century. According to the Record Office of Genoa, cannon batteries were constructed on the site in the early 16th century, and military engineer drew up plans for a full fortress circa 1554. The resultant castello was completed by 1557, and, in 1575, was instrumental in turning back an attack on the town by Giò Andrea Doria. The structure was enlarged from 1622 to 1624, and survived in this form for a century and a half. The little tower was destroyed in 1798 by an English attack during Napoleon's Ligurian Republic. The castello was abandoned after the Congress of Vienna in 1815.