Centuries of conflict have left their mark on Northumberland is the shape of castles, bastles and Roman forts.
But the county is also studded with the legacy of the two world wars and the Cold War.
The extend of what still survives increasingly interested retired engineer Ian Hall, who lives in Alnwick, and became the object of walks with wife Elaine.
“Every walk for the past five years ended up at some pillbox or other,” says Ian. “The more I looked into what was done during the Second World War, the more astounding it became.”
What remains in Northumberland includes defended beaches, more than 200 pillboxes, practice trench systems, coastal and anti-aircraft gun sites, radar stations, airfields, live firing ranges, underground “resistance” bases and Cold War bunkers.
“You realise how much is still out there, and the more you look, the more you find,” says Ian. “A lot of what was constructed was never recorded as it was all done in such a rush.”
Ian set up his own Wanney Books operation to publish his findings, and his Relics of War: A Guide to the 20th Century Millitary Remains in the Northumberland Landscape, is available at £4.50 from www.wildsofwanney.co.uk . In the First World War, Fort Coulson gun emplacement was built to protect Blyth, and was pressed into service again in the next war.
The Roberts Battery was set up near Seaton Sluice and its gun control facility is now a house.
Training trench systems were dug north of Rothbury and at Otterburn, and can still be seen in the landscape.
In the Second World War, RAF Acklington was a fighter base and some of its original buildings survive, including a pillbox with a mounting for an anti-aircraft gun on the roof.
Eight shell-proof pillboxes can be seen at Ottercops, which was a key radar installation. What was the officers’ mess also now serves as a house.
After Dunkirk, the threat of invasion was very real and a rapid programme of defence construction began.
Anti-tank concrete blocks were lined up along Northumberland beaches, with pillboxes.
At Druridge Bay, one pillbox was designed to look like a cottage.
There are also the remains of shore gun emplacements at Scremerston, and near Newbiggin-by- the-Sea and Lynemouth.
Inland “stop” lines of pillboxes were built to hold up the enemy. They followed the Coquet and Wansbeck, rivers and two subsidiary lines were built between Wooler and Belford and Wooler and Alnwick, which have survived almost completely.
Later, the emphasis was shifted to defending settlements such as Wooler, Alnwick, Belford and Morpeth, where a number of pillboxes remain.
Gun loopholes were created in existing structures and can still be spotted in places such as Alnwick cemetery wall and overlooking the town’s Lion Bridge, and near Telford Bridge in Morpeth.
“That the vast majority of these defences were constructed in less than four months is a staggering feat,” says Ian.
Pillboxes came in various designs, including the sandbag model.
Prefabricated versions, as seen near Dunstanburgh Castle, and the lozenge pillbox which can be found next to the ramparts of Old Bewick Iron Age hillfort are examples of fortifications many centuries apart.
Small auxiliary units of locals were trained to carry out sabotage raids and underground, air raid shelter-style “hides” were built for them.
Other locals were detailed to gather intelligence as they travelled around, leaving messages for units who would transmit the information from underground radio bases, some of which survive on private land.
There were RAF airfields at Eshott, Milfield near Wooler, Morpeth and Boulmer, with Druridge Bay, and sands at Goswick and Cheswick being used for live target practice for pilots.
In the Cold War there were around 30 underground bunkers in Northumberland and about half remain.