More mossy masonry

Or, From the outside looking in. Over the wall is my bird table and garden; outside the wall is a tangle of shrubs - dogwood, honeysuckle, etc - that needs tidying up. The triangular stones once stood - without their moss - around the roof of the library of a stately mansion called Hafod that stood a few miles from here towards Devils Bridge. They can be seen in the book 'Peacocks in Paradise'.