The Hollow Earth is a concept proposing that the planet Earth is entirely hollow or contains a substantial interior space. Notably suggested by Edmond Halley in the late 17th century, the notion was disproven, first tentatively by Pierre Bouguer in 1740, then definitively by Charles Hutton in his Schiehallion experiment around 1774.
An earth shelter, also called an earth house, earth bermed house, or underground house, is a structure with earth (soil) against the walls, on the roof, or that is entirely buried underground.
A bunker is a defensive military fortification designed to protect people and valued materials from falling bombs, artillery, or other attacks. Bunkers are almost always underground, in contrast to blockhouses which are mostly above ground. They were used extensively in World War I, World War II, and the Cold War for weapons facilities, command and control centers, and storage facilities. Bunkers can also be used as protection from tornadoes.
Subterranean London refers to a number of subterranean structures that lie beneath London. The city has been occupied by humans for two millennia. Over time, the capital has acquired a vast number of these structures and spaces, often as a result of war and conflict.
A tunnel is an underground or undersea passageway. It is dug through surrounding soil, earth or rock, or laid under water, and is enclosed except for the portals, commonly at each end. A pipeline is not a tunnel, though some recent tunnels have used immersed tube construction techniques rather than traditional tunnel boring methods.
A subterranean river is a river or watercourse that runs wholly or partly beneath the ground, one where the riverbed does not represent the surface of the Earth. It is distinct from an aquifer, which may flow like a river but is contained within a permeable layer of rock or other unconsolidated materials. A river flowing below ground level in an open gorge is not classed as subterranean.
An underground city is a series of linked subterranean spaces that may provide a defensive refuge; a place for living, working or shopping; a transit system; mausolea; wine or storage cellars; cisterns or drainage channels; or several of these. Underground cities may be currently active modern creations or they may be historic including ancient sites, some of which may be all or partially open to the public.
A dugout or dug-out, also known as a pit-house or earth lodge, is a shelter for humans or domesticated animals and livestock based on a hole or depression dug into the ground. Dugouts can be fully recessed into the earth, with a flat roof covered by ground, or dug into a hillside. They can also be semi-recessed, with a constructed wood or sod roof standing out. These structures are one of the most ancient types of human housing known to archaeologists, and the same methods have evolved into modern "earth shelter" technology.
An immersed tube is a kind of undersea tunnel composed of segments, constructed elsewhere and floated to the tunnel site to be sunk into place and then linked together. They are commonly used for road and rail crossings of rivers, estuaries and sea channels/harbours. Immersed tubes are often used in conjunction with other forms of tunnel at their end, such as a cut and cover or bored tunnel, which is usually necessary to continue the tunnel from near the water's edge to the entrance (portal) at the land surface.
Subterranean fiction is a subgenre of adventure fiction, science fiction, or fantasy which focuses on fictional underground settings, sometimes at the center of the Earth or otherwise deep below the surface. The genre is based on, and has in turn influenced, the Hollow Earth theory. The earliest works in the genre were Enlightenment-era philosophical or allegorical works, in which the underground setting was often largely incidental. In the late 19th century, however, more pseudoscientific or proto-science-fictional motifs gained prevalence. Common themes have included a depiction of the underground world as more primitive than the surface, either culturally, technologically or biologically, or in some combination thereof. The former cases usually see the setting used as a venue for sword-and-sorcery fiction, while the latter often features cryptids or creatures extinct on the surface, such as dinosaurs or archaic humans. A less frequent theme has the underground world much more technologically advanced than the surface one, typically either as the refugium of a lost civilization, or as a secret base for space aliens.
A yaodong is a particular form of earth shelter dwelling common in the Loess Plateau in China's north. They are generally carved out of a hillside or excavated horizontally from a central "sunken courtyard".
Livability or liveability is the degree to which a place is good for living. Livability refers to the concerns that are related to the long-term wellbeing of individuals and communities. It encompasses factors like neighborhood amenities, including parks, open space, walkways, grocery shops and restaurants as well as environmental quality, safety and health. It also incorporates things like cost and friendliness. These features contribute to the pleasantness and accessibility of communities. Additionally, livability considers the availability and quality of public transport, educational institutions and healthcare facilities. It also considers the overall cultural and social atmosphere of a place, including the presence of diverse recreational activities and community engagement opportunities. All these factors combined create an environment that enhances the overall quality of life for residents.
The Zimmerberg Base Tunnel (ZBT) is a railway tunnel under the Zimmerberg mountains in Switzerland. Phase I of the tunnel was opened to traffic during April 2003.
Subterranea are underground structures, both natural and human-made. Some subterranea and related topics include:
Cisternerne is an exhibition space for contemporary art in Copenhagen, Denmark with one annual site-specific total experience - and a wide range of events during the year. Cisternerne is an integral part of the Frederiksberg Museums (Frederiksbergmuseerne) where the singularity of its architecture and atmosphere remains a core attraction.
A cave dweller, or troglodyte, is a human who inhabits a cave or the area beneath the overhanging rocks of a cliff.
Subterranean fauna refers to animal species that are adapted to live in an underground environment. Troglofauna and stygofauna are the two types of subterranean fauna. Both are associated with hypogeal habitats – troglofauna is associated with terrestrial subterranean environment, and stygofauna with all kind of subterranean waters.
Subterranean warfare or underground warfare is warfare conducted underneath the ground surface. It is predominantly conducted in tunnels and underground cavities, both natural and artificial.
Underground construction refers to the construction of underground tunnels, shafts, chambers, and passageways, it is also sometimes used to describe the portion of traditional construction that takes place below grade.
An earthscraper is a building that provides multiple stories of permanent space below ground where people may live: the inverse of very tall high-rise buildings.
