Marietta is a city located in central Cobb County, Georgia , and is its county seat.

As of the 2000 census, the city had a total population of 58,748, making it one of metro Atlanta's largest suburbs. Census estimates of 2005 indicate a population of 61,261. Marietta is the third-largest of three principal cities (by population) of and is included in the Atlanta-Sandy Springs-Marietta, Georgia metropolitan statistical area, which is included in the Atlanta-Sandy Springs-Gainesville, Georgia-Alabama (part) combined statistical area.

Southern Polytechnic State University (SPSU), Chattahoochee Technical College, and Life University are located here, and the city operates Marietta City Schools, its own school district separate from the Cobb County Public Schools. Dobbins Air Reserve Base is on the south side of town, separated from SPSU by a Lockheed-Martin manufacturing plant.

The major landmark in Marietta is the Big Chicken, a large, metal, animated chicken structure atop what is now a KFC, located east of downtown at one of the city's busiest intersections - Cobb Parkway and Roswell Street. Even as the city has become more urbanized, locals still refer to it when giving directions.

The city also operates Marietta Power under the auspices of the Board of Lights & Water (BLW). The BLW is also party to the Cobb-Marietta Water Authority. The city formerly operated Marietta FiberNet, a fiber optic network, but was forced to sell the network to American Fiber Systems after substantial losses.

Downtown Marietta Square, features Glover Park, the historic town square and former location of the county courthouse. Incorporated in 1982, Theatre in the Square is a year-round professional theatre, producing a five-show subscription season as well as summer and holiday shows. It is one of the Southeast's most respected regional arts institutions, consistently ranked as one of Georgia's top professional theatres. The Strand Theatre is currently being renovated back to its original design and will open to feature classical films. The Marietta Gone with the Wind Museum, also called "Scarlett On the Square", houses one of the world's most extensive collections of memorabilia related to both the book and the film. Wine tasting are hosted regularly at the Marietta Wine Market. Other places of note on the square are, Shillings on the Square, Cool Beans, the Vineyard Café, Three Bears Café, Eddies Trick Shop and Marietta Pizza Company.

The CSX freight trains between Atlanta and Chattanooga (Western & Atlantic Subdivision) still run a block west of the town square, past the train depot (now the visitor center) and the Kennesaw House, one of only two buildings in Marietta not burned to the ground in Sherman's March to the Sea. (The third was later burned by angry locals when it was discovered the owner was a spy for the Union.)

As of 2007, the mayor of Marietta is Bill Dunaway, who was owner and president of Dunaway Drugs, a former local retail chain of drugstores based in Marietta from the late 1920s until it was sold to Eckerd Drug in 1989.

Marietta's sister cities are Heredia, Costa Rica and Linz am Rhein, Germany.