Recent archaeological works have revealed evidence of rare seeds ("medicinal products from all over the known world"), used for medicinal treatment as well as what may be medical waste in this area, including over 200 teeth. The experts found little above-ground evidence of the hospital because its stones had been removed long ago. Dr Brian Moffat, who led the investigation, estimated in 1993 that the peak years for the hospital were "from around the middle of the 12th century to perhaps the middle of the 15th" with perhaps 300 people residing there to deal with visitors and patients.