Finished in 1943, the Pentagon is a symbol of U.S. military might. It's also one of the places attacked on 9/11.
Construction on the Pentagon started on Sept. 11, 1941, in the midst of World War II. The five-sided design was chosen to accommodate existing roads around the building's original site near Arlington National Cemetery; a different site was ultimately picked, but the design was kept, according to the History Channel.
July 23 is National Hot Dog Day! Learn more about the tasty food, from where it originated from to what it's made of.