The Jan. 5 article "Sites of Distinction" in the Prince George's Extra incorrectly identified the location of Riversdale Mansion. The historic home is in Riverdale Park. (Published 01/12/2000)

It's no great secret that Prince George's County is one of the country's most significant historic regions. The National Register of Historic Places lists nearly 80 sites in the county, and tells a rich and varied story of centuries of human activity, as represented by archaeological sites, armories, historic homes, railroad buildings, churches, airports and even the Washington-Baltimore Parkway.

Special notice in such an area is a high honor, but there's another, even more exclusive level of recognition to be had: a listing, by the federal government, as a National Historic Landmark. This designation, separate from the Register of Historic Places and given personally by the Secretary of the Interior, results from a lengthy and exhaustive process of nomination and review. Only six locations in Prince George's County--three historic plantation homes, a NASA building, one natural area and a Depression-era planned community--have so far made the cut.

"It's a national honorific," says John Sprinkle, supervisory historian of the National Historic Landmarks Survey in Washington. "I like to explain it this way--a landmark is the kind of place you might find in a textbook on American history."

The first Prince George's location to receive such status, in 1964, was the site of Accokeek Creek, in Piscataway Park. According to Jim Rosenstock, a park ranger with National Capitol Parks-East, the site was originally chosen because of its archaeological significance as an especially rich source of information on American Indian life prior to British arrival.

The Accokeek Historic Landmark has special meaning for Maryland's Piscataway Indians. In 1979, the Piscataway received special authorization from the federal government to allow the burial of Chief Turkey Tayak, a crucial figure in the tribe's 20th-century history, on national parkland near the creek. American Indians from Maryland and elsewhere visit the site regularly, paying homage to one of their modern-day heros.

"It's a sacred site for many Indians," Rosenstock says, "and it's also a beautiful, unspoiled natural area." Landmark designation, though it includes no direct funding, does help to ward off developers, and that allows visitors at Mount Vernon, immediately across the Potomac, to enjoy a landscape similar to the one George and Martha Washington would have seen from their veranda.

Three historic houses--Riversdale Mansion in Riverdale, His Lordship's Kindness in Clinton and Montpelier Mansion in Laurel--are landmarks, due in large part to their importance as exemplars of early American architecture. So, too, is the entire city of Greenbelt, designed out of whole cloth as part of President Franklin D. Roosevelt's New Deal venture in planned low-income communities. Landmark designation was granted to Greenbelt two years ago, just in time for the city's 60th anniversary celebration.

Perhaps the county's most unusual historic landmark--and the only one not open, in some form, to the public--is the Spaceflight Magnetic Test Facility at the Goddard Space Center. A single building in the large Goddard complex, the facility was built in the 1960s (and is still used) to test the effect of the earth's magnetic field on the electrical systems of unmanned spacecraft. According to Sprinkle, the facility was chosen by the Landmark Survey in 1984 as part of a "Man in Space" theme and represents Goddard's enormous contributions to American exploration in space.

Sprinkle emphasizes that Landmark designations are often grouped around such themes, and that nationally significant sites--perhaps some of the 75 or so other "Historic Places" in Prince George's County--can certainly fall through the cracks.

"We're after a certain level of significance--the first or finest of this, the only one of that," Sprinkle says. "But there's nothing to say that there aren't other sites just as worthy, and we're looking all the time."

ACCOKEEK CREEK SITE--Mockley Point, in Piscataway Park off of Bryan Point Road. Free; closes at dusk. For information, call the Fort Washington Park Visitor's Center at 301-763-4600.

GREENBELT MUSEUM--10-B Crescent Rd., Greenbelt. Open Sundays, 1 to 5 p.m., and by special request. Free. For special tours and information, call 301-507-6582.

HIS LORDSHIP'S KINDNESS--7606 Woodyard Rd., Clinton. Open Fridays, 1:30 to 5 p.m. Also open each second and fourth Saturday, noon to 5 p.m. For fees and information, call 301-856-0358.

MONTPELIER MANSION--Route 197 and Muirkirk Road, Laurel. One-quarter mile west of the Baltimore-Washington Parkway. Open for public tours on Sundays noon to 4 p.m. March through November. For fees and information, call 301-953-1376.

RIVERSDALE MANSION--4811 Riverdale Rd., Riverdale, off of East-West Highway between Route 1 and Kenilworth Avenue. Open Sundays from noon to 4 p.m. Weekday group tours are available by appointment. For fees and information, call 301-864-0420.

CAPTION: Historic landmark His Lordship's Kindness, a Georgian plantation home built in 1787 by Robert Darnall, is in Clinton.

CAPTION: The north facade of Riversdale Mansion, which is a National Historic Landmark. The property is open noon to 4 p.m. Sundays.