The approximate two-square mile area lying north of Northwest Highway, south of Walnut Hill Lane, east of Midway Road and west of Preston Road remain the essential original boundaries of Preston Hollow, which is often now termed "Old Preston Hollow."
The boundaries of Preston Hollow as defined by the schools the children attend is land to the north of Northwest Highway (Loop 12), south of Forest Lane, east of Midway Road and west of North Central Expressway (US 75).
Hope that helps,
Keith W Hefner
Halo Group Realty, LLC
If not, many people in Dallas incorrectly use the "generalization" of the area that is: South of LBJ, North of Northwest Highway, east of the Toll Road, and west of Central Expressway as "Preston Hollow."
Marsh Lane is not in Preston Hollow.
There are maps online that will show you the actual Preston Hollow neighborhood. The link from Peter is one referenced commonly. Some of the most prime pieces of land within Old Preston Hollow are actually west of the Toll Road and East of Inwood, south of Walnut Hill.