The border begins here
Berwick's on the English-Scottish border and, although now part of England, changed hands repeatedly in the Middle Ages in the wake of Anglo-Scottish conflict (and the football team plays in the Scottish league). Linked to this, the area was noted for 'border reiving' - essentially cross-border rains by clans in the days when law and order was a concept rather than a reality
Mainly due to the area's disputed status, there are a number of castles here which are well worth a visit - my favourite is Etal Castle, which can be combined with a trip to the battlefield at Branxton (although the battle itself is referred to as Flodden) - this is where a Scottish invasion foundered, with the Scottish King included in the list of those killed
The view of Bamburgh castle, near Seahouses (chapter 3) is spectacular, but, although I haven't visited it myself, I gather it's disappointing once you get inside
Berwick itself has signs of its past, with a castle remnant at the railway station and, more imposingly, a complete wall circuit with beautiful views of the town and the river Tweed
The sea is warmer than you might think - I was able to swim off one of Berwick's beautiful beaches quite comfortably (summer only though!) and there are other great beaches close, such as Dunstanburgh
There are 2 main attractions on the coast, both of which I emphatically recommend:
1) Lindisfarne - lots of tourists, but go and you can see why - it is regarded as the cradle of English Christianity; the venerable Bede based himself here, as did Cuthbert, prior to Viking raids.
2) Seahouses - in itself an average seaside town but with access to trips out to sea in search of puffins and seals. We were too late in the year to see the puffins, but the seals still made it worthwhile!