Beautiful masonry work adds a lot to a home, and it can improve the way your house looks. However, when poorly maintained or very old, it could actually do the opposite. There are many ways that your masonry could take damage from the environment, but in most cases, prevention will save you a lot of trouble later on.
Water is one of the most damaging things to masonry, especially in areas where there is a chance that the water will freeze, since this can expand small cracks and destroy the masonry. To keep water away from your walls, make sure the grade around your house is sloping away and that there is proper drainage. You might also want to treat the surface of your masonry with a compound that will keep water away, especially if it already is old and has some cracks in it.
Vegetation should be trimmed away from the masonry, especially vines that will attach themselves to the wall.