Multi-Tiered City

Multi-tiered Cities (MTC) or commonly called "Double Decker Cities" are large cities that have multiple floors. This increases population density, thus, saving space, yet retaining a larger population. Both names are used interchangeably, however, Mult-tiered Cities is the preferred name because not all cities in the future will be limited to two tiers.

Locations
Most Multi-tiered Cities are commonly found in Tessan, however, Paesiodon has one, as does Sur du Opilli. Pesseton plans to develop a similar system in high population areas. In Tessan, many of the cities surrounding Baetin Bay are normal cities, however, a few of them have been converted into the MTCs.

Design
Most MTCs feature two levels, with a third service and emergency level below ground. Above ground, a large plate holds up the top floor. The plate his held up by large columns (usually about five- eight), which are often filled with a shopping center with elevators up to the top floor. Many older cities had a central support column that was designed to support the upper floors, however, many of the new cities do not have this feature, and instead, have a large curved dome ceiling. Most recently, a new model called RAC 470- 37F has been designed by Metropole Inc. This company designed Tessopoli, and their newest model is a three floored. Initial testings are occuring on deciding how and where to build it.

Health and Safety Concerns
Many people view the cities as environmentally friendly, since they can support more people in the same amount of terrestrial area. However, many people fear that it damages the Earth due to problems with over crowding and inability to dispose of waste. Another con of the Multi-tiered city is the lack of sunlight. Many people are beginning to show signs of Vitamin D deficiency  due to long time in the center of the city. As the cities get larger, it becomes more difficult to access natural sunlight to produce Vitamin D. A modern problem comes from disturbance of the circadian cycles. However, implementation of "Blu-Light 37" has allowed people to moderately control their cycles again. The intensity of the Artificial Circadian Light System implemented in the ceiling of modern cities is controlled by outdoor sensors placed around the perimeter, and side, the lights change intensity (the greatest is during the mornings) to help people keep biological cycles in check. A modern problem plaguing many cities is called Echo Pollution. Echo Pollution arises when sound is constantly echoing around a room. This echo, in many cities can be heard on the lower deck, especially around the edges, where rumbling and an assortment of other sounds are reflected. This causes sleep disturbance and other advers health effects. To solve this problem many cities are retrofitting panels to either absorb or scatter the sound and prevent the chronic Echo Pollution. A final common concern is geological, in that many people fear earthquakes and tropical storms.

Costs
Since the area inside remains constant, housing prices increase exponentially. Building costs