Place
- Ohio--Scioto County1
- Ohio--Seneca County1
- Ohio--Toledo1
- Ohio--Trumbull County1
- Ohio--Vinton County1
- Ohio--Wyandot County1
- Olentangy River1
- Olloy-sur-Viroin, Belgium1
- Omø By, Denmark1
- Oostduinkerke, Belgium1
- Orchimont, Belgium1
- Oregård, Denmark1
- Ottowa River1
- Ovtrup, Denmark1
- Paliseul, Belgium1
- Pallenbour, Belgium1
- Palluau, France1
- Panama1
- Panama Canal1
- Pecq, Belgium1