The Great Clock of Westminster has experienced periodic stoppages and maintenance issues since its construction in 1859. Major events include being silenced during World Wars I and II, slowing due to bird nesting and heavy snow, and undergoing its longest repair period of 26 days in 1976 when a part broke. Routine maintenance stoppages generally last less than two hours, but occasional longer stoppages of up to six weeks have occurred since 2000 to repair bearings and bells.