Maryland Route 355 (MD 355) is a 36.75-mile (59.14 km) north–south road in western central Maryland in the United States. The southern terminus of the route is in Bethesda in Montgomery County, where Wisconsin Avenue meets the county's border with Washington, D.C. The northern terminus is just north of a bridge over Interstate 70 (I-70)/U.S. Route 40 (US 40) in the city of Frederick in Frederick County, where the road continues north as Market Street through Frederick toward MD 26.
MDÂ 355 serves as a major thoroughfare through Frederick and Montgomery counties, passing through Bethesda, Rockville, Gaithersburg, Germantown, Clarksburg, Hyattstown, Urbana, and Frederick, roughly parallel to I-270. The southern portion of the route from the Washington, D.C., border to Germantown is a suburban four- to six-lane divided highway lined with many businesses. North of Germantown, the route is predominantly a two-lane rural road until it reaches Frederick, where it passes through commercial areas in the southern part of the city. The road changes names along its route: from south to north, it is called Wisconsin Avenue, Rockville Pike, Hungerford Drive, Frederick Road, and Urbana Pike.