O

Old Burying Ground, Halifax, Nova Scotia, Canada

Old Exchange & Provost Dungeon, Charleston, United States

Old Synagogue, Krakow - Poland

Oliver Cromwell's House, Ely, England

Olympia Greece

Orihuela Town Wall Museum - Spain

Ostia, Italy

Oude Kerk (Old Church) Amsterdam, Netherlands

Our Lady of the Assumption Cathedral, Ajaccio, Corsica

Our Lady of the Assumption Cathedral, Oaxaca, Mexico

Our Lady of Victories Church, Quebec City, Canada