PRINCE GEORGE'S County historic preservationists had always suspected that the falling down, white stucco structure behind the venerable Saint Mary's Church in Upper Marlboro was old. They looked at the house's colonnaded porch, its hip roof, cream-washed exterior and other features and figured maybe a mid-19th-century construction. What they didn't know was that the Victorian-era architecture was just a facade. Hidden within its walls lay the remains of a much older dwelling. One hundred fifty years old? More like 300.

The discovery came in 1975, just as county officials were preparing to level the place to make room for a parking garage. Talk quickly turned from razing the property to raising funds for a restoration. It took eight years for the Maryland-National Capital Park and Planning Commission (M-NCPPC) to appropriate the necessary $900,000, and another five years of research, design and construction before the house opened to the public for tours.

What you see today when you visit the landmark known as Darnall's Chance is an early Georgian brick structure, older than any other in Upper Marlboro and perhaps in the county. Certain architectural elements make the building unique among surviving Maryland Colonial houses: projecting quoins (wall surfaces) and a central bay on the exterior front of the house, and the way the cedar roof shingles wrap around the upper-story windows.

As much as its age and architecture, Darnall's Chance is noteworthy for its history. First owner Henry Darnall was an immensely wealthy merchant and politician who owned more than 27,000 acres in Prince George's County alone, as well as large landholdings throughout Maryland. Historians speculate that Darnall used this residence as a town house, a kind of showplace, at a time when Upper Marlboro was a bustling center of activity within the colony. (Darnall's main abode would have been his plantation, the Woodyard, located along what is now Woodyard Road, near Andrews Air Force Base.)

Darnall's granddaughter Eleanor eventually inherited the property and lived here with her husband, Daniel Carroll. Records seem to indicate this is where Eleanor gave birth to her two famous sons: Daniel Carroll, delegate to the 1787 Constitutional Convention and signer of the United States Constitution, and John Carroll, the first bishop of the Roman Catholic Church in America. Other prominent Upper Marlboro citizens have called Darnall's Chance their home, including Lettice Lee of the Lee family dynasty. The M-NCPPC bought the house in 1974 from Harry Buck, whose family had owned the property for nearly 70 years, the longest of any owners.

A guided tour takes you through all three floors of the house. Although less than 30 percent of the 1695 structure remains, workers were able to reproduce an authentic version of the interior because of "ghosts," traces in the plaster and brick of original moldings, trim and shelves. You can see one of these ghosts, the outline of a shelf, in the first-floor dining room, at the juncture of the end wall and the entrance to the modern wing housing restrooms and a catering area. (The house is also available for rent as a special event site.)

Elsewhere on the main level are the ballroom, which was added in the 1850s, Mrs. Darnall's front bedroom and the long central hall. It's hard to believe that most of what you see is new, but the deception is intentional. Construction workers employed early 18th-century techniques throughout the restoration process. Wooden pegs fasten the woodwork more often than nails, all of the windows are made of hand-blown glass, hand-wrought rosehead nails hold down the floor boards of uneven width, and hand-forged hooks and staples keep the wooden tri-fold shutters in place when opened.

Upstairs rooms, once bedchambers, now display exhibits re-creating dramatic moments in Maryland's life and tracing the history of the Darnall family, Darnall's Chance and Upper Marlboro.

Of all the different areas in the house, the basement has survived the most intact. Much of the bluestone flooring is original, as are the walls carving out the large wine cellar, the kitchen with its wide hearth and a room, now the gift shop, that historians think may have been slave quarters. Artifacts, some dating from 1650, are on view here: the remains of wine bottles, oyster shells, delftware, chamber pots, animal bones, brass pins and other items that hint at the way the house's earliest inhabitants lived.

One of the most intriguing features of Darnall's Chance lies not within the house but in its back yard: a burial vault. Archaeologists unearthed the large brick underground crypt in November 1987, just when they thought their property dig was coming to a close. The vault appears to be the same one referred to in a 1788 deed conveying ownership of Darnall's Chance from one of Lettice Lee's daughters to another family.

Mounds and mounds of kitchen garbage had been heaped upon the site for 150 years or more, obscuring the burial plot from view. The garbage, especially the oyster shells, turned out to be useful, though, for they were instrumental in preserving the skeletal remains of the nine bodies that lay here. But who were they?

A man age 38 to 59, two women, a boy of 13, a girl of 6, three babies and a newborn are the answers thus far. Experts, including the park and planning commission's history division archaeologist, Don Creveling, and the Smithsonian's Dr. Douglas Owsley are still analyzing the remains, so the total picture's not in yet. County historians wonder whether the man and woman might have been Lettice Lee and one of her three husbands.

The M-NCPPC isn't through with Darnall's Chance -- the agency has plans to restore the crypt, re-inter the remains, develop an exhibit that explains Colonial burial practices, landscape the estate in accordance with early 18th-century designs and place historic period furnishings throughout the house, among other things. In the meantime, you can drop by most Sundays for a quick lesson in early American lifestyles and Upper Marlboro history.

DARNALL'S CHANCE -- 14800 Gov. Oden Bowie Dr., Upper Marlboro. 301/952-8010. From the Beltway, take Pennsylvania Avenue/Route 4 south (Exit 11A) and head seven miles to the Upper Marlboro exit. Turn left on Water Street, right at the first light onto Main Street and left at the next light onto Gov. Oden Bowie Drive. Turn right at the first driveway into the grounds. Open for walk-in tours from noon to 4 Sundays and by appointment 9 to 4 Monday through Friday. Admission is $1 for adults, 75 cents for seniors and 50 cents for students. Good wheelchair accessibility.

Elise Ford last wrote for Weekend about local wineries.