Probably most professionals working in stone masonry and architecture have iconic landmarks that inspire them, and Ralph Petrillo is no exception. While whittling down to a single piece of architecture is difficult, I can say with confidence that Edinburgh Castle places fairly high on my list of favorites. For those of you who are unfamiliar, Edinburgh Castle is nestled on the historic Castle Rock in Scotland and is one of the capital’s main attractions, welcoming over one million visitors each year. Castle Rock was formed over 340 million years after a volcano eruption. For centuries, the rock was used as…