They were built to ward off the threat of invasion in the darkest days of the Second World War - and now a pair of pillboxes are being opened to the public.
Two restored defensive structures at Sheringham Park will go on show as part of the National Trust's Heritage Open Days.
A spokesperson said: "These were part of the defences of this section of the coast.
"Two slightly different designs can be seen in conjunction with other nearby defensive structures. These, along with maps of the complete defensive layouts, enable a good understanding of the plan of defence."
Around 18,000 pillboxes were built around the British coastline during the Second World War.
The pillboxes will be open on Thursday (September 16) and Friday from 11am-4pm. Bookings are not required.
Heritage Open Days events are taking place across the county.
There are more than 300 free events happening including walks, performances and tours.
visit www.heritageopendays.org.uk to find out more.
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