The main purpose of a house is to provide shelter, security and privacy for the occupant. All these factors were taken into consideration not only in the form of houses that were built but also in the settle ment plans of the communities.
In her illuminating study of African traditional architecture, Susan Denver identified several major styles of architecture, three of which are particularly relevant to Nigeria, namely the Round, the rectangular and the Impluvial. She defines style as not only the form of individual buildings but also the way they are arranged (Denver, 1975). The Round style was usually free standing, walled with mud, thatched roof and arranged in clusters of buildings.
The Rectangular style was characterised by having mud wall, thatched saddle or hipped roof and free standing. In the Impluvial style, which was common in the forest area of the southern part of Nigeria, four buildings were arranged in a rectangular form to enclose a courtyard.
With regard to settlement plans, there were differences among the various communities. In lgboland, for example, Cole and Aniakor identified major factors that influenced settlement planning. These were population density, topography, water location social organisation, the need for defence and local traditions (Cole and Aniakor, 1984). In some other instances, related families lived in one space, or sometimes in sections of quite large houses, as in Cross River and Akwa lbom States. However, compounds as units of social organisation were emphasised in many Nigerian traditional communities and this was often reflected in their architecture.
USE OF LOCAL MATERIALS
Apart from ease of procurement, locally sourced materials appeared to possess other qual ities which enhanced their use in the building trade. It is known that walls erected in thick layers ensured strength and stability of the building while thick thatched roofs with overhanging eaves ensured that the buildings were were shady, cool, and ventilated. A Polish Professor of Architecture, carried out a survey of Nigerian traditional architecture between 1958 and 1965. Not satisfied with this singular effort and obviously fascinated by the ingenuity of the traditional architect, Dmochowski returned to Nigeria in 1972 to embark on the ambitious task of reconstructing some of the major ancient traditional building types to create the present Museum of Traditional Nigerian Architecture (MOTNA) in Jos.
In this monumental work, Dmochowski demonstrated in practical terms not only how various ethnic groups constructed and decorated their houses but also the way the builders solved, using indigenous technology, the complex problems associated with architecture. The ancient Kano city walls, the Zaria mosque, the Palaces of the Emirs of Bida, llorin and Abuja, among others, were built to specification. These reconstructed buildings and the few old ones that have been preserved stand as testimony of Nigeria's past achievements in traditional architecture.