That picture is definitely of the Initiation Well at Quinta de Regaleira, clearly got the same patterned floor as in the photo halfway down the page pvpeacock linked. Search might have lead you astray if you were looking for a site in Braga.
I believe you are correct . The internet seems to have had a brain fart! The photo I posted clearly says it’s a feature of the Church of Bom Jesus in Braga and describes the staircase! https://www.boundlessroads.com/landmarks-in-portugal/‘\
So you are up