From my first-grade classroom in the Southworth School on Meeting House Hill -- one of the highest points in Boston -- I used to gaze out upon the Boston Harbor Islands and daydream. My fantasies involved pirates and buried treasure, and featured a certain little boy who played the hero upon the ramparts of the island forts.

Just that word, "fort," had an inexpressible charge of romance. To think that there were "forts" in Boston!

Yet while I could dream about the islands and their forts -- could even, in later years, visit one of them, Castle Island, connected by causeway to South Boston -- I could not get to them. The islands were for boatsmen, yachtsmen -- nautical types who owned a boat or could man a boat to sail there. In short, in my boyish thinking, you had to be a WASP to get to those islands; they were Protestant islands, somehow, relics of the old Yankee hegemony over Boston, which my people, the Irish, had ended long before I was born. As I saw it, the Yankees, having lost the city, repaired in boats to the harbor islands. They were a sort of consolation prize.

No more. Since 1976, this once-aristocratic preserve has been considerably democratized. Seven of the roughly 30 harbor islands have been made into a state park; they are now owned by the masses, of whom your correspondent, of a recent Saturday afternoon, was one.

Over the years the harbor islands -- located about 10 miles from the city of Boston and ranging in size from 16 to 188 acres -- have been used for farming, for sundry institutional purposes (to house prisoners of war and victims of incurable disease) and for coastal defense. Now the islands of Peddocks, Gallops, Bumpkin, Grape, Lovells, Great Brewster and Georges are open to the public, visitable by ferries, water taxis and private boats, and used mainly for picnicking, hiking and fishing. Swimming is permitted on Lovells, but it is not wise, the harbor being disgracefully dirty. A visitor can only note the irony -- pristine public islands in waters fouled by private greed and public indifference -- and report that, spurred by a court order, the state is moving to clean up one of the more capacious and beautiful harbors in the nation.

My wife and son and I set off for Georges, the main island, on a day whose comfort index I can best describe by saying that it was your typical Washington summer day; in short, approaching the unbearable. No sooner had the boat put off from its moorings at the old Hingham shipyards than one felt in a different climate -- one breeze-refreshed and sweater-cool.

The Hingham boat -- a two-deck affair complete with snack bar and capricious toilets -- put out from Hewitt's Cove into Hingham Bay. Sailboats danced on the water; condos loomed up on the shore. Here was the good life. And yet my heart sank at the sight of the deserted Hingham shipyard now disappearing behind us. It sank further at the even more desolating prospect of the Quincy Shipyard, whose crane rose up at the base of the bay like a giant petrified crab.

Fore River, as the old shipyard was called, turned out destroyers and cargo ships for both World Wars. My father worked there as a steamfitter, and I was weaned on stories about the pride in workmanship and the esprit de corps among the employes of Bethlehem Steel, which owned the yard. Men made a paycheck out of Fore River, certainly, but in my father's telling they worked for a higher goal -- to help win the war. This sense of dedication to a cause nobler than money-making died out when Fore River changed ownership and was closed down several years ago. Few of the men who helped to win our world can now afford to live in the harbor condos, or to gad about in the sailboats that make the islands cruise such a happy feast for the eye.

To get out of Hingham Bay and into Boston Harbor our boat had to sail through Hull Gut, a narrow strait between the Hull peninsula and Peddocks Island. Peddocks, a the largest of the park islands at 188 acres, was the site of Fort Andrews, a military post from 1904 through World War II; it was then converted to a prisoner-of-war camp that held nearly 1,800 Italian soldiers. It is now open to camping and picnicking; its West Head is a fragile salt marsh and wildlife sanctuary.

Peddocks, too, had for this emotionally susceptible passenger its plangent note: a red-roofed white church, disused, deserted, a monument of a vanished age. Looking at that church, you could close your eyes and hear the buzz of a fly trapped during a long-forgotten Sunday service decades ago; and you could see the men in the congregation, their thoughts straying from the sermon to the afternoon roast, or to that moment on the walk over the hill after the service when their wives, conscious of no onlookers, would tenderly clasp their hands. The church lent itself to such fancies, and the traveler alive to the softer vibrations should visit it and the forested island on which it sits.

For the military-minded traveler, Georges Island abounds in sterner pleasures. Here sits Fort Warren, which from 1860 to the Second World War covered the main channel leading into Boston with cannon huge, formidable, and never tested.

Park rangers give tours of Fort Warren, and on one of these we heard the story of "the Lady in Black," whose unquiet spirit is said to still haunt the granite bastions of the fort.

The Lady in Black was the wife of one of the 800-odd Confederate prisoners kept on Fort Warren during the Civil War. She could not bear being parted from her husband, so she made her way to Massachusetts and with the help of some Southern sympathizers got herself decked out as a Union soldier and sailed a boat out to the island. Somehow, she located her husband and was on the point of escaping with him when the colonel in command of the fort appeared on the scene. She drew a pistol, aimed at the colonel's heart and squeezed the trigger. The gun exploded, sending a shard of hot metal into her husband's skull. He died on the spot. And she soon joined him in death -- hanged for her part in his escape. Her last request was that she be allowed to die looking like a woman. No dress being available, she was got up in some black cloth -- hence her cognomen, the Lady in Black.

After hearing this tale and others like it from the tour guide, we climbed up to the rear wall of the fort, and there before us was a magnificent sight -- the whole immense Outer Harbor of Boston, dotted with sailboats, lighthouses and, distantly, big ships carrying goods to the old city as ships have done for 300 years. That spectacular vista alone is worth, as they say, the price of admission.

Fort Warren -- a really imposing structure -- made me wish I were a 10- or 12-year-old boy, and could shoot imaginary guns from the real embrasures at the imaginary pirates (sailboats) in the harbor beneath, beyond and all around. Boring daddies and mommies can wonder at the expense involved in building the fort -- as well as the forts on the surrounding islands -- to defend against a threat that never materialized. It was a case of the Bostonians of the 1820s remembering the last war, that of 1812, when the British burned Washington and attacked Baltimore; the Bostonians were afraid of being taken by sea. Work was begun on the harbor forts in 1834, and completed in time to defend Boston from the Confederate Navy, which was unable to defend Charlestown Harbor, in South Carolina, much less to launch a fleet against Boston.

From Georges, I could see Gallops to the west. The 16-acre island looks like a fine place to get away from the crowd (considerable) on Georges. Flat and beachy, Gallops could be a piece of Cape Cod. I was told that there are World War II installations on the island -- including a school for Army chefs (if that phrase is not an oxymoron) -- and that from its landward side, the views of the Boston skyline will take your breath away. Sunset cruises to these islands are also available. Evening, indeed, might be the best time to make the trip: Picture the sun setting over Boston, its glass towers holding the last light while darkness falls on the city beneath.

For the historically-minded family, then, for young lovers, for students of deindustrialization, a tour of the Boston Harbor Islands can be most heartily recommended. My 5-year-old son was too young to appreciate my lecture on the cost and follies of national defense. I hope that some future daddy, to whom our lives will seem as poignant as the lives of the people who once thronged that church on Peddocks Island now seem to us, will not find a text to expostulate upon a vine-covered laser gun or other relic of the Strategic Defense Initiative.

Jack Beatty is a senior editor at The Atlantic Monthly.