Northumberland () is a county in North East England, one of the two counties in England that border on Scotland (the other is Cumbria). Notable landmarks in the county include Alnwick Castle, Bamburgh Castle, Hadrian's Wall, Hexham Abbey and the tidal island Lindisfarne with the accompanying Lindisfarne Castle.

Northumberland is bordered by land on three sides: by the Scottish Borders region to the north, by County Durham and Tyne and Wear to the south, and by Cumbria to the west. The fourth side is the North Sea, with a 103-kilometre (64 mi) stretch of coastline to the east. Northumberland is a predominantly rural county with a landscape of moorland and farmland, and a large area of it is part of Northumberland National Park. The county has been the site of a number of historic battles with Scotland.