This 100 year old, 8 foot tall, dry stone retaining wall near Wilkes Barre, PA that Mary and I discovered while on our way to Washington DC, incorporated thousands of small thin shims to level the different thicknesses of sandstone blocks, as well as bed the stones together in a fairly successful, attractive looking, 'mortarless' structure.
The wall breathes, lets dampness through and hold back thousands of tons of rubble and stays together, and still looks pretty good after so many years. A concrete or cement structure would have 'given up' years ago.
