Saw this on the map many times, so I was in the area and checked it out. Its not so megalithic, but it's certainly mega. The Peaks' answer to Monument Valley.
Named after St Peter's in Rome; the domed top of the outcrop similar in shape to that of the church there.
A handaxe was discovered in the scree close-by and was perhaps associated with a barrow that is speculated to have been located in this area.
It was also the location of the Peak's last gibbeting in 1815.