LITERATURE REVIEW

environment. Considered only suitable for overly complex sites and programs by architects and urban planners before the 1970s, underground spaces have been built for a wide variety of reasons (Carmody & Sterling, 1993, p.3). An underground facility provides:

 The ultimate “green roof” above ground they do not impact the surface aesthetic while leaving space for natural ground surfaces and flora.

 Underground structures are less susceptible to physical intrusion and natural disasters.

 They also offer constant temperatures, and since subterranean buildings are not susceptible to the fickle nature of aboveground weather, they require less energy.

 Ancient people built the famous underground city of Cappadocia in Turkey for protection against both weather and war. They were constantly being attacked.

 The inhabitants retreated belowground during emergencies.

 The primary reason for digging underground cities in the ancient world was for protection. (“Underground Cities,” 2019)

Today, subterranean architecture is mystique. It has a certain intrigue to it, playing between fear and fantasy. Uncovering and discovering new sensations, playing on this perspective of creating new congregated yet dispersed space. Although it cannot be suggested that underground space represents the optimal solution for buildings, it can be considered as a suitable alternative when considering complex sites, programs, and building functions, making underground space a viable alternative to conventional above-ground buildings. 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, storage cellars, cisterns, drainage channels, or several of these. A human can live underground for a long time when all life support systems are mechanical. The more that can be made with minimal moving, or mechanical parts, the longer humans could remain underground. Underground bunkers or caverns need ventilation, climate control, groundwater removal, food production, and light and energy sources. Underground spaces are used to a great extent and potential benefits therein are being exploited, however, these operations are done without sufficient strategic management. As competition for space below ground increases, the likelihood of conflicts between potential benefits or existing structures will increase. Hence, more stringent management of ‘underground space potential’ is required to avoid irreversible waste of resources. However, little research has been undertaken on the essential role the subsurface plays, as a part of our landscape in a sustainable future. This includes finding feasible underground solutions that might help relieve pressures on the surface. From this point, questions then arise as to how we can incorporate the use of underground space to create a more sustainable future, or how we can make robust decisions to achieve the goals of sustainability that will facilitate a move from fragmented decisionmaking to holistic, whole system thinking? How can we protect our societies during times of great uncertainty where life would be impossible on the ground? The challenge here is how cities incorporate new thinking about a potential third dimension of land use into what they do now while ensuring that what they do now will provide benefit in the future. (Mastenbroek, 2021)

2.2. Historical development of underground space:

The history of subsurface use goes back to the Neolithic age when underground passages served as a hiding place for primitive populations (Sterling and Godard, 2000).

2.2.1. Derinkuyu:

The volcanic rock landscape of Turkey’s Cappadocia region is pockmarked with several different underground cities, but perhaps none is as vast or as impressive as Derinkuyu. This labyrinthine complex dates to around the eighth century B.C. and was built to serve as a refuge during periods of war and invasion. Its 18-story interior was a self-contained metropolis that included ventilation shafts, wells, kitchens, schoolrooms, oil presses, a bathhouse, a winery, and living space for some 20,000 people. When threatened by attack, each level of the city could be sealed off behind a collection of monolithic stone doors. Historians believe that the Hittites or the Phrygians were among Derinkuyu’s earliest builders, but