Tower 7, as it's known, is 65 years old and 110 feet tall, scratched with graffiti and whipped by decades of salty ocean winds - but it remains nearly as solid as the day it was hurriedly built by a country on the verge of war.

Horace Knowles is 84 and about 5-foot-10. He is still standing tall, too, despite circulatory problems and respiratory issues that force him to use a portable oxygen tank when he takes his memory-stirring walks through the dunes over which the tower looms.

Once, they - the tower and Knowles - shared a mission.

Knowles was one of about 2,000 soldiers dispatched - nearly a year before Pearl Harbor - to a barren stretch of beach near the mouth of the Delaware Bay to build a fort and man the heavy artillery that would protect America's shores from enemy attack.

Tower 7 is one of 11 curious concrete cylinders that rise from Delaware's coastline, from its southern edge in Fenwick Island to Cape Henlopen, all built to provide a vantage point from which the coordinates of enemy ships could be relayed to gunners, such as Knowles, stationed in nearby bunkers.

As it turned out, no enemy ships were ever fired upon. The low-profile oceanfront fort, as radar and weapons technology progressed, was obsolete even before World War II was over. And Knowles' unit, the 261st Coast Artillery, quietly went out of existence afterward, its work protecting America's coast rating only a paragraph or two, if that, in most history books.

What was known as Fort Miles all but disappeared when, in 1963, the federal government began turning the land over to Delaware's state park system.

Once the site of one of the heaviest concentrations of artillery on the East Coast, it became Cape Henlopen State Park, a place for vacationers to forget about their troubles and frolic in the sun.

Concrete block barracks became vacation cottages. What was once a gun battery became a bathhouse. The fort's brig became a nature center. And the wharf used to service mines laid in the Delaware Bay became a fishing pier.

As for the towers, they've endured far longer than anyone expected, including the Army Corps of Engineers, which predicted - because beach sand was used in mixing the concrete - they would only last about 20 years.

Instead, they've stood three times that long, most of that time idly, surviving freeze and thaw, careless tourists, and, in the case of the two towers across from Gordon's Pond in the state park, the ocean itself.

Although built nearly a quarter-mile from the shoreline, both now have waves lapping at them during high tide.

Mostly, for 40 years, they served to shelter sea birds and baffle beachgoers: Were they ugly lighthouses? Lifeguard stations? Silos for storing extra beach sand?

Tourists wondered, and while park employees did their best to explain, misconceptions spread.

"The younger generation is not well aware of what went on in these towers," Knowles said as he walked down a path in the state park. "And it's a damn shame."

Knowles, who after the war went on to a career with DuPont, the chemical company, takes walks in the park three times a week, clutching a bag that contains his portable oxygen, wearing a cap that says 261st Coast Artillery and - as skateboarders and bicyclists whiz by - recalling days when this swath of beach served a far different purpose.

Generally, his walks are undisturbed. But the other day, he said, a woman stopped him. "She said, 'You were stationed here, weren't you?' I said yes, and she thanked me. She said, 'Thanks for doing that.'"

Knowles paused to catch his breath. "There's not many people that thank us."

'A barren place'