The place is miles and miles of chambers and tunnels which look very similar. The first mine I did solo was Rhosydd on the other side of town which is tiny by comparison and it still took me 3 visits to find one of the inclines, it is however, a fairly easy mine to navigate.
Just to put it in perspective Oakeley across town which was once the largest underground slate mine in the world had over 50 miles of underground tramway.