Stone walls come in many shapes and sizes. Some aren't stone at all, but concrete poured and scored to "look like stone." Some are nearly boulders,  piled roughly as if they belong on a mountainside. Others are carefully constructed puzzles fitting together thin and elegant slabs of granite. Still others are craggy concrete, jackhammered up from a driveway and frugally, sustainably repurposed as a chunky slab wall. 

They all serve a special purpose: to delineate the space around a house, create an entrance and border, and perhaps hold up a mound of earth as well. The reasons for a wall vary, but a stone wall provides a solidity and permanence that fences just can't. Renaissance architects building urban palaces in Florence knew this, creating imposing rusticated ground floors for the palazzi that the 1% lived in.