Sheffield is a city located in the county of South Yorkshire in England. The town is known for it's steel, and is also the hometown of Def Leppard. Founding members Joe Elliott, Rick Savage, Rick Allen, Steve Clark and Pete Willis were all born in the town. Joe and Sav where born in the Crookes region of the city, with Clark being born in the nearby Hillsborough.
For more information on the town itself, see the Wikipedia article: Sheffield