If you want to create a boundary between your yard and the sidewalk without building a fence, use large rocks. Create a simple line around the edge of the yard, focusing on the front edge. Choose rocks that are roughly the same size so the fence has a uniform look. Don't worry about the rocks being the same shape; a bit of natural variation adds visual interest to the fence. Try to arrange the rocks at least 6 inches to 1 foot from the sidewalk to avoid creating a hazard for pedestrians or snow removal.
Turn a large rock or two into the centerpiece of a large-scale Zen garden. Line part of your yard with sand or very small crushed gravel; you may create a flowing shape in one corner of the yard or along the side of the house to give the garden an anchor point. In the center of the gravel, place one or two large rocks. Use a rake to create flowing lines around the rock. The simplicity of the decoration works equally well with a modern landscaping design or a flowing garden.
If your front yard has a garden or a border, you can work large gardens into the design. Clear a space in the garden in the middle of some of the plants and shrubs. Place a large, textured rock in the space. If you don't have a garden, put plants around the rock as a starting point. The rock becomes a focal point of the garden and provides a contrast to the natural edges of the plants.
Create a natural landscaping look by working big rocks into hedges. Plant hedges around the house, choosing varieties that are approximately the same height. Choose a large rock that is no more than a foot shorter than the hedge, and select a spot for it in the middle of a row of hedges. Trim an area back in the hedge so part of the rock fits in like a puzzle piece; allow the other half to stick out.