Suggest you if possible? have a look up the pipe, a very strong torch and a mirror??
If no water has ever flowed? sounds like a redundant pipe,
What has possibly happened is hat the old pipe is a similar size as a sewer pipe from [say] a toilet. If the property has had several make overs then that could account for the pipe?
Should be possible to chop the pipe flush with the wall and fill with cement
Ken.