503 may refer to:
In general 503 (number), a number in the 500s range AD 503 (), 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. 503 Squadron RAF, an Interwar British Royal Air Force bomber unit 503 Field Battery, Royal Artillery, British Army
Warships , a Japanese WW2 submarine , a German WW2 submarine , a U.S. WW2 tank landing ship
, a Turkish navy frigate , a U.S. Navy patrolboat , a Turkish navy corvette , a Japanese Maritime Self Defence Force submarine , an Israeli navy corvette , a Philippine navy tank landing ship , a U.S. Navy ship , a WW2 U.S. Navy destroyer , a South Vietnamese green-water navy ship
Transportation 503 Kingston Rd (street car line #503), Toronto, Ontario, Canada; a tram line service
Vehicular Allison 503, a turboprop aeroengine Rotax 503, an aeroengine
Avro 503, a British military seaplane Potez 503, a French military airplane Latécoère 503, a French flying boat LEAF Antares 503, a Ukrainian ultralight
BMW 503, a grand tourer Fiat 503, a small family car
British Rail Class 503, passenger train class
Other uses 503, a music track by Hans Zimmer on the Angels & Demons soundtrack 503 Service Unavailable, a computer networking HTTP status code Elliott 503, a computer FN 503, a semi-automatic pistol manufactured by FN Herstal A type of jeans, commonly in Levi's and Edwin A type of steel used for making bicycle frames
See also
Flight 503 503rd (disambiguation) DIII (disambiguation) (503 in Roman numerals)