Certain industrial activities require transportation facilities e.g. ports, railway stations, etc. to lower transportation costs.
Various combinations of activities tend to be kept apart e.g. residential areas and airports, factories and parks, etc.
Other activities are found together to their mutual advantage e.g. universities, bookstores and coffee shops, etc.
Some facilities need to be set in specific areas in a city - for example the CBD requires convenient traffic systems, and many factories need an abundant source of water
Certain events benefit from the adjacent distance like the positions of factories and residence.
In some cases, some constructions are located in less-than-ideal locations, often due to outside factors such as rent.