503 (disambiguation)
503 may refer to: == In general == 503 (number), a number in the 500s range AD 503 (DIII), a year in the Common Era 503 BC, a year Before the Common Era == Places == Area code 503, a North American telephone area code in northwestern Oregon Country code +503, for El Salvador 503 Evelyn, asteroid #503, the asteroid Evelyn, the 503rd asteroid registered, a Main-Belt asteroid Highway 503, a list of roads named "503" Blaine School District No. 503, Whatcom County, State of Washington, USA == Military units == No.