Dr. Jekyll's mansion is a location in "Nowhere to Hyde", an episode of Scooby Doo Where Are You! It is home to Dr. Jekyll and Helga, his live-in maid.
Since Dr. Jekyll claimed that his great-grandfather was also a scientist, the laboratory (and therefore the mansion) could have belonged to the latter (and possibly other relatives, too).
Scooby Doo Where Are You!
Insert details here.
- Although not explicitly stated, the mansion could be retconned into being situated in Coolsville, the home town of the gang during their pre-adolescence, as established in A Pup Named Scooby-Doo.
- It's unknown what happened to the mansion, or Helga's job, when Dr. Jekyll was taken into custody.