of our visitors are welcomed to go there and read about it and learn about it. then we have this wonderful memorial that was built in the 1980s by -- designed by architects from howard universityn great partnership with mt. vernon, put together this really special memorial. at the time it was the only memorial to enslaved people in north america anywhere. so we're proud of that story. but somewhere in there and around there is where i would bet william lee is buried. >> time for maybe just one or two more questions. robert from annandale, virginia. good morning. thanks for waiting. >> caller: thank you very much for taking my call. my question isn't really about his presidency but your thoughts on his remarkable mother and his remarkable sister betty and her husband louis. and their influence on george. they were probably his longest female relationships, even including his wife, and i'd be interested in your thoughts. thank you. >> thank you very much. i didn't catch the third part of that question. he asked about george washington's mother and about his sister betty. i didn't hear the third part. but let me just say about the mother, you know, mary washington is really an ex