Fourteen round brick structures stand enigmatically along the Suffolk coast, part of a much larger network that stretches all the way from Aldeburgh to Seaford in Kent.
These are the Martello Towers, a string of 19th century fortresses that attracts interested travellers to this day.
Two such travellers, James "JJ" Johnson and Daniel Falvey, decided that their mission was visit them all, and they did so over eight days in an 1980s convertible, earlier this year.
Mr Johnson said: "Both growing up in Folkestone, home to the first tower, Daniel and I had always been aware of these strange upturned flowerpots – the Martello Towers.
"As Covid restrictions meant travelling abroad was difficult, we were looking at UK trips we could do.
"For something with a difference, we settled on the Martello Towers – with good history, a clear and doable route in a week, and at the site of many other interesting English holiday destinations along the way."
"The Martello towers were built very early in the 19th century" Mr Johnson said. "They were commissioned during the Napoleonic wars by prime minister William Pitt the Younger.
"The British government were really worried about a plan Napoleon had to invade, so their solution was to build this line of 103 towers down the coast.
"Primarily they were built as active defences, with cannons mounted on their roofs, though they also filled a role as a communication network."
However, the French threat to Britain was permanently negated after their fleet was destroyed at the battle of Trafalgar.
"They were planned, built and never used. Well, one in Eastbourne fired a shot at a French merchant ship once.
"The situation reminds me of the current pandemic" Mr Johnson added. "Better to be prepared than not."
"The most surprising Martello tower was the R tower in Felixstowe, underneath the (former) Bartlet Hospital.
"It's very interesting how its use has changed from a 19th century fort to a 21st century block of flats."
"Another of the Felixstowe towers is used as a storage building for the golf course, while the P tower at Martello Park is in use by National Coastwatch.
"Also, the eastern ones are built differently to the southern ones: the ones on the south coast used half a million bricks, while the ones on the east coast are broader and used three quarters of a million."
Some of the Martello Towers on this coast, including one at Shingle Street and one near Alderton, have been converted into houses, offering a uniquely secure home on the coast, for those who have the wherewithal to maintain them.
"We managed to get into a few of the Martello Towers which have been done as homes, and talk to the owners, and well, the refurb process sounds like a very tough job."
"You're living in something that isn't meant to be a home, it wasn't built for it.
"They're hundreds of years old — as people redevelop them they find all sorts of peculiar things, like twisting chimneys."
"Some are also very isolated. They haven't had any pipes laid or anything."
"The real excitement was was seeing how the towers work as waypoints, leading you along the Suffolk coast, and up into the estuaries".
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