Century tower clocks were tower clocks manufactured by Nels Johnson, designed to last 100 years. They were "clocks built to last a century," hence the name "Century" tower clocks. These tower clocks were mostly produced from 1880 to 1910. Johnson, by himself, made between 50 and 60 of these clocks.Johnson designed and manufactured these tower clocks at his machine shop in Manistee, Michigan. He built the clocks by himself and had no employees.