Marietta Diner is the most striking restaurant in Marietta, Georgia. Literally. You can see its neon sign from miles away! It has one of the largest parking I have ever seen at a restaurant, and it's always, always, always crowded. If you go, you'll probably have to wait between 5 and 30 minutes, but the turnover is fairly quick.
The restaurant has many good points. First, the location: on Cobb Parkway, near the exit onto Highway 285. Also, the original 50's-style architecture with the Cadillacs parked out front. Finally, and most importantly: THE FOOD. You have to go hungry or at least willing to share because the portions are huge. The serve a typical diner menu with hamburgers, pastas, sandwiches and salads, but as the owners are Greeks, they also have several pages of Mediterranean food, even things like paella. I personally recommend the Meatball Sub, the Philly Cheestake (meat, cheese and green peppers) and gyros and souvlakis which are finger-licking good. Oh and the "Frank Sinatra" pasta! Wow! I need to stop writing, I'm getting hungry!