WW1 - Looking down on after deck and fighting tops of USS Nevada - pictured before her 1927 refit. Lattice masts, or cage masts, are a type of observation mast common on major warships in the early 20th century. They are a type of hyperboloid structure, whose weight-saving design was first used by the Russian engineer Vladimir Shukhov. They were used most prominently on American dreadnought battleships and armored cruisers of the World War I era. Date: circa 1918