Offices can range from a single room above a shop to an office building within a factory complex to a city centre office block. Offices may broadly be classified into a number of different categories: those designed primarily to provide office accommodation and that are generally a purpose designed building; those where the public may gain access, such as banks and building societies. The offices of categories also includes are those that are ancillary to alternative uses, such as offices in industrial complexes; and offices above shops and other properties. The most important evidence for any rating assessment will be the actual rent agreed on the property, particularly if both it is close to the valuation date and the lease terms are similar to the basis of rateable value. The valuation must reflect market conditions at the antecedent valuation date and changes in the state of the economy can be reflected only at the next revaluation.