According to Country Life, October 2002, "Alnwick is the most picturesque market town in Northumberland, and the best place to live in Britain". The town is situated largely on the south bank of the River Aln, south of Berwick-upon-Tweed and the Scottish border, inland from the North Sea at Alnmouth and north of the city of Newcastle upon Tyne.
The town dates back to about AD 600, and over the centuries has thrived as an agricultural centre; as the location of Alnwick Castle and home of the most powerful medieval northern baronial family, the Earls of Northumberland; as a staging post on the Great North Road between Edinburgh and London, and latterly as a modern rural centre and dormitory town. The fabric of the town centre has changed relatively little, and retains much of its original character; but the town has grown a lot over the last ten years, with several housing estates covering what had been pasture, and new factory and trading estate developments along the roads to the south of the town.
Alnwick was an ancient parish in the Coquetdale Ward which became a civil parish the 19th century. Denwick was originally a part of the parish which was made into a separate civil parish in 1894. Alnwick was an urban district from 1894 until 1974. Other than Bondage without Alnwick, Alnwick did not have any townships within its parish and remains as a civil parish today. In 1974 rural districts were abolished and Alnwick became part of the Alnwick District until 2009 when Northumberland became a unitary authority.
The history of Alnwick is the history of the castle and its lords, starting with Gilbert Tyson, written variously as "Tison", "Tisson", and "De Tesson", one of William the Conqueror's standard bearers, upon whom this northern estate was bestowed. It was held by the De Vesci family (now spelt "Vasey" – a name found all over south-east Northumberland) for over 200 years, and then passed into the hands of the house of Percy in 1309.
At various points in the town are memorials of the constant wars between Percys and Scots, in which so many Percys spent the greater part of their lives. A cross near Broomhouse Hill across the river from the castle marks the spot where Malcolm III of Scotland was killed during the first Battle of Alnwick (1093). At the side of the broad shady road called Ratten Row, leading from the West Lodge to Bailiffgate, a stone tablet marks the spot where William the Lion of Scotland was captured during the second Battle of Alnwick (1174) by a party of about 400 mounted knights, led by Ranulf de Glanvill.
Hulne Priory, outside the town walls in Hulne Park, the Duke of Northumberland's walled estate, was a monastery founded in the 13th century by the Carmelites; it is said that the site was chosen for some slight resemblance to Mount Carmel where the order originated. Substantial ruins remain.
In 1314, Sir John Felton was governor of Alnwick. In winter 1424, much of the town was burnt by a Scottish raiding party. Again in 1448 the town was burnt by a Scottish army led by William Douglas, 8th Earl of Douglas and George Douglas, 4th Earl of Angus.
Thomas Malory mentions Alnwick as a possible location for Lancelot's castle Joyous Garde.
The Alnwick by-pass takes the A1 London – Edinburgh trunk road around the town. It was started in 1968.