The CBD  

Characteristics
The CBD or Central Business District is the commercial centre. It contains the main shops, offices and financial institutions of the urban area. It is usually the most accessible (easy to get to) part of the city. This is because most of the main transport routes lead here.
Due to high land values, buildings tend to be tall and building density is high.

Land Values
Land values tend to be very high, this is the result of great competition to locate here. It is cheaper to build up than out. Also, there is a limited amount of open space available. New developments tend to focus on redeveloping existing areas rather than using the limited open space available.

Population Density
During the day the CBD is densely populated. This is due to the high number of pedestrians and shop and office workers. However, the CBD has a limited number of houses and flats due to the high land values in this area.