State Route 110 (SR 110) is a primary state highway in the U.S. state of Virginia. Known as Richmond Highway (formerly Jefferson Davis Highway), the state highway runs from U.S. Route 1 (US 1) and Interstate 395 (I-395) in Crystal City north to I-66 in Rosslyn within Arlington County. SR 110 is a four- to six-lane freeway that parallels the Potomac River, providing a connection between several of Arlington's urban villages. The state highway also provides access to the Pentagon, which is the headquarters of the United States Department of Defense, the grounds of Arlington National Cemetery, and SR 27, an east–west freeway between the Pentagon and the cemetery. SR 110 is a part of the National Highway System for its entire length.