CHARLESTON, S.C. (AP) -- The founder of the Slave Dwelling Project is scheduled to give an update on his three-year effort to preserve old slave dwellings around the nation.

Joseph McGill is to give a talk Wednesday at The Old Exchange Building in Charleston's historic district.

For three years, McGill has been sleeping in old slave dwellings in an effort to draw public attention to the need to preserve the buildings that are part of the nation's history.

McGill is a field officer for the National Trust for Historic Preservation and is based in Charleston. He has slept in 38 buildings in 12 states so far.