9,860 articles
Olynthus, House A 11
Olynthus, House A 11: an irregularly planned Classical Greek house (ca. 432–348 BC) near the agora of Olynthus, Halkidiki, built against the west fortification wall, 17.7 × 21.3 m, with unspecialized rooms around a courtyard and no kitchen, andron, or pastas.
Oman Botanic Garden
Oman Botanic Garden (حديقة النباتات العُمانية) is a 430-hectare botanic garden near Al Khoudh, Muscat, dedicated solely to Oman's native flora, with two climate-controlled biomes, the world's largest documented Arabian plant collection, completed and handed to Muscat Municipality in December 2025.
Omayed Biosphere Reserve
Omayed Biosphere Reserve, a UNESCO MAB site in Egypt's Mediterranean coastal desert designated in 1981, covering 75,800 ha with five habitat types, Bedouin communities, and severe dune loss from irrigation-driven land conversion.
Ombak KLCC
Ombak KLCC is a retail, art and lifestyle destination in Kuala Lumpur's KLCC precinct, opened 21 August 2026 by KLCC Holdings, anchoring the relocated GALERI PETRONAS gallery.
Omega Park
Omega Park (Parc Oméga) is a 2,200-acre drive-through wildlife park in Montebello, Quebec, opened in 1991, with a 12-km car safari, about 20 species, wolf lodges, and CAZA and AZA accreditation.
Omiya Park Small Zoo
Omiya Park Small Zoo (大宮公園小動物園) is a free-admission zoo in Omiya Park, Saitama City, Japan, keeping about 60 species and 300 small animals and birds since 1953.
Omo Biosphere Reserve
Omo Biosphere Reserve, a UNESCO MAB rainforest site in Ijebu, Ogun State, Nigeria, 135 km northeast of Lagos. Designated 1977, Nigeria's first; 95,610 ha; known for endemic butterflies and about 100 forest elephants; threatened by logging and cocoa farming.
ONE nuotykių parkas
ONE nuotykių parkas, also UNO Park Druskininkai, is a tree-climbing adventure park in Druskininkai, Lithuania, run by UAB UNO Parks, with 6 adult and 4 children's routes, 55 km/h Nemunas River zip lines, and a 21 m free-fall jump.
Oneida Casino (United States)
Oneida Casino is the Green Bay, Wisconsin gaming enterprise of the Oneida Nation of Wisconsin, opened 1994 under a 1991 state compact; official casino of the Green Bay Packers, distinct from the New York Oneida Indian Nation's Turning Stone.
Onion Portage Archeological District
Onion Portage Archeological District (Paatitaaq) is a National Historic Landmark on the Kobuk River in Kobuk Valley National Park, Alaska, with over 70 cultural layers spanning about 10,000 years, from the Akmak complex to Arctic Woodland Eskimo, and continuing subsistence caribou hunting.
Onnum
Onnum (Hunnum), the Roman fort at Halton Chesters, Northumberland, on Hadrian's Wall in wall mile 21; unique L-shaped plan from a Severan western extension, about 1.75-2 ha, garrisoned by a part-mounted cohort then the Ala I Pannoniorum Sabiniana.
Onon Balj Biosphere Reserve
Onon Balj Biosphere Reserve, a UNESCO MAB site in Khentii and Dornod provinces, Mongolia, designated 14 June 2023 around Onon-Balj National Park at the forest-steppe transition of the Onon and Balj River basin near Chinggis Khan sites.
Ontario Heritage Act
Ontario Heritage Act (OHA), R.S.O. 1990 c. O.18: Ontario statute enacted 1975 enabling municipal designation of individual heritage properties (Part IV, s. 29) and heritage conservation districts (Part V), plus ministerial provincial designations and Stop Orders.
Opatów
Opatów, a Polish town, is known for the largest fully excavated Przeworsk culture cemetery (site 1, ~1,000 features, 300 years of use) and the Globular Amphora culture cemetery at Sadowie; also a historic Jewish community.
Open-air display of Great Patriotic War military equipment
Пляцоўка баявой тэхнікі часоў Вялікай Айчыннай вайны: open-air displays of WWII-era Soviet combat equipment at memorials such as Loyev's Battle of the Dnieper museum, Stalin Line, and the Minsk war museum, showing T-34, IS tanks, Katyushas, and artillery.
Opimiano
Opimiano (Villa of Rufinus Vinicius Opimianus): Roman villa site at Grottaferrata near Rome's Via Latina and Ad Decimum catacombs, attributed via an inscription to the senator Opimianus, on two terraced substructures.
Opryland USA
Opryland USA, a country music-themed amusement park in Nashville, Tennessee, operated 1972 to 1997 before closing for the Opry Mills mall; its rides were sold to Premier Parks.
Optatiana
Optatiana: Roman auxiliary fort and vicus at Sutor, Sălaj County, Romania, in Dacia Porolissensis, on the Tabula Peutingeriana; garrisoned by the numerus Maurorum Optatianensium, a Moorish cavalry unit of about 500 men.
Orăştiora de Sus
Orăștioara de Sus, a commune in Hunedoara County, Romania, holds Sarmizegetusa Regia, the Dacian capital, other UNESCO Orăștie Mountains fortresses, and a Roman auxiliary fort at Bucium with Trajanic and Hadrianic phases.
Oratory (chapel)
Орнітарій (oratoriy, Latin oratorium) is a private chapel in Western Christianity for a specific community's rites, protected by canon law; the same prayer houses gave the name to the musical oratorio genre.
Orbaniacum
Orbaniacum, also Orbigniacum, a Gallo-Roman vicus near Tours identified with Orbigny, Indre-et-Loire, France; a church was built there under Bishop Euphronius per Gregory of Tours, Hist. X.31; Pleiades 138503, Barrington Atlas 14 G1.
Orbe Gallo-Roman Villa
Orbe-Boscéaz, the Orbe Gallo-Roman villa in Vaud, Switzerland, is the country's largest known Roman rural estate (16 ha), built around 160-170 CE and famed for nine mosaics, the richest set north of the Alps.
Orchestra in the Agora of Athens
Orchestra in the Agora of Athens: the 6th-century BC performance area, also called Agora orchestra, at the center of the Athenian Agora, with a circular platform and wooden ikria stands, abandoned after their early 5th-century BC collapse in favor of the Theater of Dionysus.
Orchid and Butterfly Valley
Orchid and Butterfly Valley (蝶谷幽兰) is a 7,208-square-meter orchid and butterfly garden in Fairy Lake Botanical Garden, Shenzhen, opened in 2009, with three sections conserving over 300 orchid species and attracting live butterflies.
Orchid Resort Dogashima
Orchid Resort Dogashima (らんの里堂ヶ島, Ran no Sato Dogashima) was an orchid garden in Nishiizu, Shizuoka, founded 1968 as Dogashima Western Orchid Center, reopened 2006, closed July 31, 2013; not the Dogashima onsen hotels.
Ord River Floodplain
The Ord River Floodplain is a Ramsar wetland of international importance covering 140,766 hectares at the Ord River's mouth near Wyndham in the Kimberley, Western Australia, listed in 1990.
Ordesa-Viñamala Biosphere Reserve
Ordesa-Viñamala Biosphere Reserve, a UNESCO MaB site in Huesca, Aragon, Spanish Pyrenees; designated 1977 with Sierra de Grazalema as Spain's first biosphere reserves, expanded 2013 to 117,264.99 ha around Ordesa y Monte Perdido National Park.
Oregon Caves National Monument and Preserve
Oregon Caves National Monument and Preserve is an NPS unit near Cave Junction, Oregon, protecting a rare 4.8 km marble solution cave, the River Styx subterranean waterway, Pleistocene fossils, and the 1934 Chateau, established 1909 and expanded 2014.
Öremölla
Öremölla: Roman Iron Age high-status cremation grave in southern Scania, Sweden, found 1872; cremated male with Roman cauldron refitted with local-style male face masks, the oldest Scanian Iron Age male depiction.
Örendibi
Örendibi is an archaeological ruin site near Sömek village, Silifke, Mersin Province, Turkey: a Roman to early Byzantine farm settlement with a three-nave church, olive-oil works, and a lintel bearing semeion, thunderbolt, and shield reliefs.