SALEM, N.H. -- At the far end of the ''oracle chamber," an opening in the roof admits soft sunlight into the long, narrow rock room. On the left, we glimpse the secret hideaway, just large enough for a person to curl up and peek out through a small opening at the bottom. Above it, a narrow, rock-lined tunnel, called the ''speaking tube," extends through 5 feet of stone wall, ending beneath the ''sacrificial table," a 4 1/2-ton grooved slab. Straining to read our printed guide, we wish we had brought a flashlight.
We are exploring America's Stonehenge, thought to be the oldest man-made structure in the country. There is no question these tunnels and shelters of rock were designed for human habitation; carbon techniques have dated the site to 2000 BC.
The builders of the site were seeking more than shelter, however. Huge standing stones around the main complex are believed to have been used for solar and lunar alignments in prehistoric times. The maze of rock signposts and stone walls reflects the rotation of the sun and the position of significant stars, making the site a gigantic astronomical calendar.
Known for years as ''Mystery Hill," the site was opened to the public in 1958 after Robert Stone began researching the massive structures. In an introductory video, Stone says there are many sites in the Northeast that reflect the Megalithic period, roughly 3500-1500 BC, though few are as extensive as this one.
Who built America's Stonehenge remains a mystery. These talented masons could have been the forebears of Native Americans, or they could have been visitors from Europe, since many of the stone chambers resemble ancient monuments of Europe, such as the more famous Stonehenge in southern England. That circle of 26-ton stones is thought to date from about 2800 BC.
From an observation tower at the site's highest point, visitors look down on the spider web of stone walls that crisscrosses the 30-acre property, marked by huge boulders and carved stone slabs. The stones mark the position of the sun and moon at the summer and winter solstices and spring and fall equinoxes; they also accurately record the position of the moon in a lunar cycle, which takes about 18 1/2 years.
This is a pleasant, peaceful place, offering thought-provoking history questions for adults and ample climbing and exploring possibilities for children. It takes about an hour to walk the relatively flat, half-mile trail and see the stone structures. In winter, visitors can rent snowshoes to explore the site and some 105 acres of surrounding woodlands.
Ethan Randall, 14, a student at the Bromfield School in Harvard, saw the attraction in a brochure and persuaded his parents and his sister, Victoria, 6, to visit on a Saturday last month. He found it ''a cool historical site, definitely worth going to." The Randalls split up, with two of them talking through the speaking tube in the oracle chamber and the other two waiting by the sacrificial table to see if the words seemed to float up from beneath the stone slab.
''It really worked," Ethan said.
With all the mystery surrounding it, America's Stonehenge is taking full advantage of Halloween. The site is partnering with Ghostlight Theater Co. to present ''Tales Among the Ruins" Oct. 20-22 and 27-29. A trick-or-treat mix of storytelling and live action, the guided tour will cover astronomical oddities, tales, and superstitions surrounding the site. Call or visit the website for details.
Contact Ellen Albanese at email@example.com.