Interstate 495 (abbreviated I-495) is a freeway-class interstate highway which circles Washington, D.C. and its inner suburbs in Maryland and Virginia. I-495 is widely known as the Capital Beltway or simply the Beltway, especially when the context of Washington, D.C. is clear. It is the basis of the phrase "inside the Beltway", used when referring to issues dealing with American government and politics. Interstate 95 utilizes the southern and eastern half of the Capital Beltway to circumnavigate Washington, D.C., and is cosigned with Interstate 495 along that route.

The circumferential roadway is located not only in the states of Virginia and Maryland, but also crosses briefly through the District of Columbia over the Potomac River on the Woodrow Wilson Bridge. There is also a short spur of the Beltway in Maryland. The Cabin John Parkway, a short connector between I-495 and the Clara Barton Parkway near the Maryland-Virginia border, is considered an Interstate spur by the Maryland State Highway Administration, and is designated I-495X. The Beltway passes through the Maryland counties of Prince George's County and Montgomery County, the Virginia county of Fairfax County and the independent city of Alexandria.