Washington Monument cornerstone time capsule

The Washington Monument's cornerstone was laid on July 4, 1848 during a Masonic ceremony; the stone setting sealed a capsule containing coins and other documents of the era. The Monument's early construction and long hiatus in building make the original cornerstone and its time-capsule contents a historically notable, less-visible element of the National Mall. The monument was completed later in the 19th century and remains one of the city's most prominent but internally historical features.