- An independent city in Virginia, USA.
- Various other towns and cities, including:
- A CDP in Alaska, and the borough seat of Petersburg Borough.
- A city in Illinois, and the county seat of Menard County.
- A city in Indiana, and county seat of Pike County.
- A small city in Monroe County, Michigan.
- A small city in Nelson County, North Dakota.
- A town in Lincoln and Marshall Counties, Tennessee.
- A small city in Hale County, Texas.
- A city in West Virginia, and the county seat of Grant County.
- a campaign in the American Civil War
- Saint Petersburg, formerly Leningrad, a city in Russia
- Saint Petersburg (city in Russia)
declension of Petersburg