The Vampire Diaries, Mystic Falls was filmed in Covington, Georgia. In addition to the Vampire Diaries, Newton County has been the location for over sixty movies including The Dukes of Havard to Show.
The iconic clock tower and Mystic Grill are located on the Historic Downtown Square. When filming started the Mystic Grill was only an exterior location. The interior shots were filmed in the studio. In 2014 the Grill was renovated and opened to the public as a restaurant. http://mysticgrill.restaurant/
Make sure to stop by Vampire Stalkers Store on the square. They have a great selection of the original movie props in addition to souvenirs. You can also book a tour with them. https://www.mysticfallstours.com/
A few blocks away are Elena Gilbert's House and the Lockwood Mansion. Both are privately owned residences. We drove by and got shots of both.
I was hoping to get a glimpse of the Salvatore House. It was located in Atlanta, Georgia, but has been torn down.