The class of possible tenants is the determining factor. On Broadway an office building attracts all sorts of tenants. On either side of Broadway, it must look for its tenants to the businesses which have made that district their headquarters. And in seeking tenants for a new building, it is wise to go after the leaders of a trade. If you get them, others in the same line will have to follow. Sometimes a skilful agent, by carefully selecting his first tenants, can practically move an entire trade to his buildings. An example of this is the way in which railroad interests have made the Hudson Terminal Building their headquarters, and this field alone made a community of fine tenants. Some of these trades require special arrangements, others need only the average layout. For example, dealers in precious stones want north light and woe be to the owner who erects a building for this trade opposite a yellow building. The reflected yellow light lowers the value of their diamonds. Other trades have certain requirements in the way of service or convenience to the post office or some other activity connected with their regular affairs. The adaptability of the building to these requirements materially influences its rentals.