Urban exploration is the exploration of manmade structures, usually abandoned ruins or hidden components of the manmade environment. Photography and historical interest/documentation are heavily featured in the hobby and it sometimes involves trespassing onto private property. Urban exploration is also called draining, urban spelunking, urban rock climbing, urban caving, building hacking, or mousing.

Avinguda de la Llum is a now-closed underground mall in Barcelona, the first one of its kind to open in Europe, open between 1940 and 1990, on a 2000 square-metre site built in 1929 and boasting 68 commercial establishments, including a movie theater. It was underneath Carrer de Pelai, between Plaça de Catalunya, Carrer de Balmes, Carrer de Bergara and Plaça de la Universitat, upstairs of the Ferrocarrils de la Generalitat de Catalunya (FGC) station Catalunya, between its vaults and the street.

Beneath the Neon: Life and Death in the Tunnels of Las Vegas is a non-fiction account by author and journalist Matthew O'Brien, with photos by Danny Mollohan. It chronicles the author's time in subterranean Las Vegas. As he pursued a killer hiding in the tunnels, he discovered hundreds of people living underground and interviewed many of them for the book. It was released in June 2007 by Huntington Press.

Buildering describes the act of climbing on the outside of buildings and other artificial structures. The word "buildering", sometimes misspelled bildering, is a portmanteau, combining the word building with the climbing term bouldering. If done without ropes or protection far off the ground, buildering is extremely dangerous. It is often practiced outside legal bounds, and is thus mostly undertaken at night.

The Cave Clan is a primarily Australian group dedicated to urban exploration.

The Cincinnati Subway was a partially completed rapid transit system beneath the streets of Cincinnati, Ohio. Although the system only grew to a little over 2 miles (3.2 km) in length, its derelict tunnels and stations make up the largest abandoned subway tunnel system in the United States. Construction began in the early 1900s as an upgrade to the Cincinnati streetcar system, but was abandoned due to escalating costs, the collapse of funding amidst political bickering, and the Great Depression during the 1920s and 1930s.

Cities of the Underworld is an American documentary television series that premiered on March 2, 2007, on the History channel. The program explores the subterranean environment and culture beneath various civilizations. The series was originally hosted and narrated by Eric Geller for the majority of episodes in season 1, with Don Wildman taking over for the rest of season 1 and seasons 2 and 3.

Dump digging is the practice of locating and excavating old garbage dumps with the intent of discovering objects which have potential value as collectibles or antiques. These dumps are sometimes centuries old, but often date to the late 19th century or early part of the 20th century. Among other things, the practice of dump digging is directly linked to antique bottle collecting and glassmaking.

Elevator surfing, also known as lift surfing, is an activity involving riding on top of elevators. Rarely, the activity may also involve jumping between moving elevators, although most elevator surfers consider this to be unwise and needlessly dangerous.

Forgotten Chicago is an organization that seeks to discover and document little known elements of Chicago's infrastructure, architecture, neighborhoods and general cityscape, whether existing or historical.

The Freedom Tunnel is the name given to the railroad tunnel on the West Side Line under Riverside Park in Manhattan, New York City. Currently used by Amtrak trains to and from Pennsylvania Station, it got its name because the graffiti artist Chris "Freedom" Pape used the tunnel walls to create some of his most notable artwork. The name may also be a reference to the former shantytowns built within the tunnel by homeless populations seeking shelter and freedom to live rent-free and unsupervised by law enforcement. The tunnel runs approximately 2.6 miles (4.2 km), from 72nd Street to 124th Street.

Modern ruins are the remains of architecture constructed in the recent past, generally in the most recent century, or since the 19th century. The term is most frequently used by people performing urban exploration of man-made architecture that is abandoned or no longer accessible to the general public, such as structures abandoned through the process of urban decay. Enough documentation on these sites may have been lost over time that this unscientific exploration resembles archaeology of ancient ruins in the methods used to collect information.

Mole people are homeless people living under large cities in abandoned subway, railroad, flood, sewage tunnels, and heating shafts. The term may also refer to the speculative fiction trope of an entirely subterranean society or a race of humanoid moles.

This is a list of manhole cover markings found in New York City.

Jeff Chapman, better known by the pseudonym Ninjalicious, was a Toronto-based urban explorer, fountaineer, writer and founder of the urban exploration zine Infiltration: the zine about going places you're not supposed to go. He was also a prominent author and editor for YIP magazine, as well as its website, Yip.org.

Privy digging is the process of locating and investigating the contents of defunct outhouse vaults. The purpose of privy digging is the salvage of antique bottles and everyday household artifacts from the past. Privy digging is a form of historical digging and is often conducted on private residential properties. Construction sites and major developments around older areas of towns and cities are also likely places to look for evidence of privies.

Roof and tunnel hacking is the unauthorized exploration of roof and utility tunnel spaces. The term carries a strong collegiate connotation, stemming from its use at MIT, where the practice has a long history. It is a form of urban exploration. Some participants use it as a means of carrying out collegiate pranks, by hanging banners from high places or, in one notable example from MIT, placing a life-size model police car on top of a university building. Others are interested in exploring inaccessible and seldom-seen places; that such exploration is unauthorized is often part of the thrill. Roofers, in particular, may be interested in the skyline views from the highest points on a campus. On August 1, 2016, Red Bull TV launched the documentary series URBEX – Enter At Your Own Risk, that also chronicles roof and tunnel hacking.

Rooftopping sometimes called roofing refers to the unsecured ascent of rooftops, cranes, antennas, smokestacks, etc., usually illegally. Rooftoppers usually take photos or videos and panoramic photographs—either a selfie by themselves or with the help of an assistant/accomplice crew from a distance. The practice of scaling skyscrapers often results in security crackdowns and arrests.
Ruin Academy is an independent cross-over architectural research center in the Urban Core area of Taipei City, Taiwan. It is 'set to re-think the industrial city and the modern man in the box' through research and a series of workshops.

The Night Climbers of Oxford is a secret society, dedicated to nocturnally scaling college and town buildings in Oxford, England. The society is noted for its political activism, controversial acts, feats of climbing and parkour, as well as urban exploration. The society was likely inspired by their Cambridge counterparts, The Night Climbers of Cambridge. Activities conducted by the society are forbidden by the University authorities, meaning that acts are completed under the cover of darkness, to avoid detection.

Tunnel People is an anthropological-journalistic account describing an underground homeless community in New York City. It is written by war photographer and anthropologist Teun Voeten and was initially published in his native Dutch in 1996, and a revised English version was published by the Oakland-based independent publishing house PM Press in 2010.

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.

RÉSO, commonly referred to as the Underground City, is the name applied to a series of interconnected office towers, hotels, shopping centres, residential and commercial complexes, convention halls, universities and performing arts venues that form the heart of Montreal's central business district, colloquially referred to as Downtown Montreal. The name refers to the underground connections between the buildings that compose the network, in addition to the network's complete integration with the city's entirely underground rapid transit system, the Montreal Metro. Moreover, the first iteration of the Underground City was developed out of the open pit at the southern entrance to the Mount Royal Tunnel, where Place Ville Marie and Central Station stand today.

Ontheroofs is an urban exploration and rooftopping photography project conceived by Vitaliy Raskalov and Vadim Makhorov, from Ukraine and from Russia respectively. Their main focus of photography is the exploration of high-rise architectural structures like skyscrapers, bridges, historic sites and cathedrals. The team have been notable for their number of free-climbs up famous buildings and monuments around the world. Typically, their videos are uploaded onto YouTube and showcase their ascent and descent. Raskalov and Makhorov appeared as recurring cast in the documentary series URBEX – Enter At Your Own Risk, which launched globally on Red Bull TV on August 1, 2016.