- Oakland, Alameda County, California1 objects
- Oakley, Contra Costa County, California26 objects
- Oakville area, Napa Valley, Napa County2 objects
- Oceania2,210 objects
- Odisha State, India6 objects
- Okinawa Prefecture, Kyushu, Japan1 objects
- Okuzuha village, Eastern Highlands Province, Papua New Guinea20 objects
- Olorgesailie, Kenya1 objects
- Olympic Peninsula, Western Washington7 objects
- Onondaga County, New York1 objects
- Ontario, Canada1 objects
- Orange County, California2 objects
- Oregon133 objects
- Oromia Region, Ethiopia3 objects
- Oroville, Butte County, California16 objects
- Oundjo (site 26), Voh commune, North Province229 objects
- Owens Valley, Inyo County, California18 objects