5. Ballston
Average home price per square foot: $475
Difference from county average:Â +$67
Real estate prices in and around this Orange Line hub are on the rise, thanks to its growing roster of tech start-ups and academic institutions (Marymount and Virginia Tech have satellite campuses here) and the innovative Defense Advanced Research Projects Agency (DARPA), plus an influx of trendy restaurants by celebrity chefs such as Mike Isabella and Robert Wiedmaier. That uptick is likely to continue with the transformation of Ballston Common mall into Ballston Quarter, signaling a boon to property values in adjacent neighborhoods such as Waycroft-Woodlawn, Bluemont and Ashton Heights.