By plane
Newcastle International Airport (http://www.newcastleairpo...) is the nearest airport to Northumberland.
By train
The principle London-Edinburgh rail line runs through the county and Berwick-upon-Tweed, to the north, is served frquently by both East Coast (http://www.eastcoast.co.uk/) and Cross Country Trains (http://www.crosscountrytr...). These operators also serve Morpeth and Alnmouth for Alnwick, though less frequently.
In most cases it is genrally more convenient to connect with the local rail network at Newcastle Central, which is served by regular trains to Edinburgh, London, the Midlands and South West. From Newcastle, Northern Rail (http://www.northernrail.org/) operate frequent services along the Tyne Valley Line towards Hexham and Carlisle, as well as serving local stations along the East Coast Main Line towards Morpeth, Alnmouth and Chathill.