Northumberland (nɔːrˈθʌmbərlənd ) is a ceremonial county in North East England, bordering Scotland. It is bordered by the Scottish Borders to the north, the North Sea to the east, Tyne and Wear and County Durham to the south, and Cumbria to the west. The town of Blyth is the largest settlement.
The county has an area of and a population of 320,274, making it the least-densely populated county in England at 64/km2. The south-east is the most densely populated region and contains the largest towns: Blyth (37,339), Cramlington (27,683), and Ashington (27,670). The administrative centre, Morpeth (14,304), is nearby to the north-west. The remainder of the county is rural, and contains Berwick-upon-Tweed (12,043) in the far north, Alnwick (8,116) in the centre, and Hexham (13,097) in the west. The county is governed by Northumberland County Council, a unitary authority. The historic county included the parts of Tyne and Wear north of the River Tyne.
To the west are the Cheviot Hills and North Pennines, while to the east the land becomes flatter before reaching the coast. The Cheviot, after which the range of hills is named, is the county's highest point, at . The county contains the source of the River North Tyne and much of the South Tyne; near Hexham they form the Tyne, which shortly downstream exits into Tyne and Wear. The other major rivers in Northumberland are, from south to north, the Blyth, Coquet, Aln, and Tweed, the latter of which forms part of the Scottish border. The county contains Northumberland National Park, the Northumberland Coast AONB, and part of the North Pennines AONB.
Much of the county's history has been defined by its position on a border. In the Roman era most of the county lay north of Hadrian's Wall, and the region was contested between England and Scotland into the Early Modern era, leading to the construction of many castles, peel towers, and the fortifications at Berwick-upon-Tweed. Northumberland is also associated with Celtic Christianity, particularly the tidal island of Lindisfarne.