Charlestown is a neighborhood found within the city of Boston, Ma. that is located between the Mystic and Charles Rivers. Originally it was it's own independent town, however, was annexed back to the city of Boston in 1847. Charlestown is a popular tourist destination within the city of Boston due to it's connection to the Freedom Trail, Bunker Hill Monument, as well as the USS Constitution which is docked in the Charlestown Navy Yard and is the oldest ship in the United States Navy. Charlestown Navy Yard was one of the first shipyards built in the United States. During its 174 year history, hundreds of ships were built, repaired and modernized, including the World War II destroyer USS Cassin Young. USS Cassin Youngwas built by Bethlehem Steel Corporation at San Pedro, California and commissioned on December 31, 1943 was maintained and staffed by National Park Service staff and volunteers. USS Cassin Young is an example of the type of ship built, repaired, and modernized and free guided tours inside the ship are provided to visitors. Charlestown has a rich history and the neighborhood, although it has undergone some large cultural changes and gentrification since the 1980's, is still defined as a predominately Irish Catholic neighborhood.