Arlington County or Arlington as it is commonly referred to is the second largest principal city of the Washington Area. Arlington is the home to many places to work with the Federal Government such as the Department of Defense at the Pentagon, the DEA (Drug Enforcement Agency), TSA (Transportation Security Administration), and DARPA (Defense Advancement Research Projects Agency). Arlington is also home to many memorials such as the National Cemetery, Pentagon Memorial, Marine Corps War Memorial, and US Air Force Memorial.