The Mount Vernon Seminary for Girls (now the Department of Homeland Security) is a 38.6-acre campus consisting of eighteen buildings that contribute to the district’s historic designation.
Seven date from 1916 to 1942 when the complex was first developed and used as the Mount Vernon Seminary for Girls.
Eleven buildings date from 1943 to 1952 when the campus was used as the U.S. Naval Communications Annex (NCA), the site of U.S. Naval cryptanalysis during and immediately following World War II.
In addition, there are seventeen buildings were constructed between 1953 and 2015, during occupation by the U.S. Naval Security Station and DHS, and are “noncontributing.”
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