Research theme 2 Church definition

CHURCH -  a building used for public Christian worship

A common architecture for churches is the shape of a cross (a long central rectangle, with side rectangles, and a rectangle in front for the altar space or sanctuary). These churches also often have a dome or other large vaulted space in the interior to represent or draw attention to the heavens. Other common shapes for churches include a circle, to represent eternity, or an octagon or similar star shape, to represent the church's bringing light to the world. Another common feature is the spire, a tall tower on the "west" end of the church or over the crossing.

Types
Basilica
The Latin word basilica (derived from Greek, Basiliké Stoà, Royal Stoa), was originally used to describe a Roman public building (as in Greece, mainly a tribunal), usually located in the forum of a Roman town.
After the Roman Empire became officially Christian, see Edict of Thessalonica, the term came by extension to refer to a large and important church that has been given special ceremonial rites by the Pope. Thus the word retains two senses today, one architectural and the other ecclesiastical.

Cathedral
A cathedral is a church, usually Roman Catholic, Anglican, Oriental Orthodox or Eastern Orthodox, housing the seat of a bishop. The word cathedral takes its name from the word cathedra, or Bishop's Throne (In Latin: ecclesia cathedralis). The term is sometimes (improperly) used to refer to any church of great size.
The church that has the function of cathedral is not of necessity a large building. It might be as small as Christ Church Cathedral in Oxford, England, Sacred Heart Cathedral in Raleigh, United States, or Chur Cathedral in Switzerland. But frequently, the cathedral, along with some of the abbey churches, was the largest building in any region.

Alternative buildings
Old and disused church buildings can be seen as an interesting proposition for developers as the architecture and location often provide for attractive homes or city centre entertainment venues On the other hand, many newer Churches have decided to host meetings in public buildings such as schools, universities,cinemas or theatres.
There is another trend to convert old buildings for worship use rather than face the construction costs and planning difficulties of a new build. Unusual venues in the UK include an old Tram power station, a former bus garage, an old cinema and bingo hall, a former Territorial Army Drill Hall, a former synagogue and a windmill.

Information from

Oxford Online Dictionary
oxforddictionaries.com/definition/church
Wikipedia
http://en.wikipedia.org/wiki/Church_%28building%29