An 18th century underground brick burial vault was discovered in 1987 during an archaeological survey of the rear yard of Darnall's Chance. In 1990, an archaeological excavation of the structure was conducted to gather information for future restoration and interpretation.

The burial vault, which measures 17 feet long, 10 feet wide and eight feet high with a stairway on the west end, is one of only two known vaults of this kind in Maryland. During the excavation it was discovered that the interior of the vault was filled with eight feet of 18th and 19th century household trash and building debris. The trash is thought to have originated from a nearby kitchen midden (trash pit) and dumped into the vault through two openings in the roof. Beneath the debris rested the remains of nine individuals -- 3 adults and 6 children – who were exhumed with the assistance of forensic anthropologists from the Smithsonian's National Museum of Natural History.

Numerous tests were conducted on the remains, including Mitochondrial DNA testing and Stable Isotope Analysis. The isotope readings determined that the five oldest individuals interred in the vault were native-born Americans. The presence of numerous cavities and slight arthritis suggest that they lived a sedentary lifestyle featuring a sugar rich diet and light workload. 
The test also aided historians in determining the identities of the three adults entombed in the vault -- Lettice Lee who died in 1776 at the age of 50, her 30-year-old brother Hancock Lee who died in 1759, and her 22-year-old sister Elizabeth who died in 1752.

The restoration of the roof, steps and sub-crypt were completed in 2002 and the remains were re-interred on June 18, 2004, in a religious ceremony attended by the descendants of Lettice Lee. To find out more about the excavation of the vault come to Darnall's Chance for a museum tour!

Source:
THE MARYLAND-NATIONAL CAPITAL PARK AND PLANNING COMMISSION
Prince George's County Department of Parks and Recreation
Darnall's Chance House Museum
http://history.pgparks.com