This is a favorite of mine , Gilfach Ddu is the name of the old slate workshops which served the various quarries above and around it , it is the home of the world renowned National Slate Museum . I really needed to get out on this Sunday as I had previously had a bit of an argument with the back of a van resulting in a badly twisted knee , it’s relatively flat in places so served its purpose well for me . Admission is free for the museum but you will have to pay for parking . The quarry you can see is the old Vivian Quarry , how a very deep pit and just above it is a lovely walk up to the quarry hospital . You must visit the cafe in the museum , good food at superb value .